@article { ISI:000303366000001, title = {Polymorphs, salts, and cocrystals: what{\textquoteright}s in a name?}, journal = {Crystal Growth \& Design}, volume = {12}, number = {5}, year = {2012}, month = {MAY}, pages = {2147-2152}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The December 2011 release of a draft United States Food and Drug Administration (FDA) guidance concerning regulatory classification of pharmaceutical cocrystals of active pharmaceutical ingredients (APIs) addressed two matters of topical interest to the crystal engineering and pharmaceutical science communities: (1) a proposed definition of cocrystals; (2) a proposed classification of pharmaceutical cocrystals as dissociable {\textquoteleft}{\textquoteleft}API-excipient{\textquoteright}{\textquoteright} molecular complexes. The Indo U.S. Bilateral Meeting sponsored by the Indo-U.S. Science and Technology Forum titled The Evolving Role of Solid State Chemistry in Pharmaceutical Science was held in Manesar near Delhi, India, from February 2-4, 2012. A session of the meeting was devoted to discussion of the FDA guidance draft. The debate generated strong consensus on the need to define cocrystals more broadly and to classify them like salts. It was also concluded that the diversity of API crystal forms makes it difficult to classify solid forms into three categories that are mutually exclusive. This perspective summarizes the discussion in the Indo-U.S. Bilateral Meeting and includes contributions from researchers who were not participants in the meeting.

}, issn = {1528-7483}, doi = {10.1021/cg3002948}, author = {Aitipamula, Srinivasulu and Banerjee, Rahul and Bansal, Arvind K. and Biradha, Kumar and Cheney, Miranda L. and Choudhury, Angshuman Roy and Desiraju, Gautam R. and Dikundwar, Amol G. and Dubey, Ritesh and Duggirala, Nagakiran and Ghogale, Preetam P. and Ghosh, Soumyajit and Goswami, Pramod Kumar and Goud, N. Rajesh and Jetti, Ram R. K. R. and Karpinski, Piotr and Kaushik, Poonam and Kumar, Dinesh and Kumar, Vineet and Moulton, Brian and Mukherjee, Arijit and Mukherjee, Gargi and Myerson, Allan S. and Puri, Vibha and Ramanan, Arunachalam and Rajamannar, T. and Reddy, C. Malla and Rodriguez-Hornedo, Nair and Rogers, Robin D. and Row, T. N. Guru and Sanphui, Palash and Shan, Ning and Shete, Ganesh and Singh, Amit and Sun, Changquan C. and Swift, Jennifer A. and Thaimattam, Ram and Thakur, Tejender S. and Thaper, Rajesh Kumar and Thomas, Sajesh P. and Tothadi, Srinu and Vangala, Venu R. and Variankaval, Narayan and Vishweshwar, Peddy and Weyna, David R. and Zaworotko, Michael J.} } @article { ISI:000306942300059, title = {Polymorphs, salts and cocrystals: what{\textquoteright}s in a name? (vol 12, pg 2147, 2012)}, journal = {Crystal Growth \& Design}, volume = {12}, number = {8}, year = {2012}, month = {AUG}, pages = {4290-4291}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, issn = {1528-7483}, doi = {10.1021/cg300704b}, author = {Aitipamula, Srinivasulu and Banerjee, Rahul and Bansal, Arvind K. and Biradha, Kumar and Cheney, Miranda L. and Choudhury, Angshuman Roy and Desiraju, Gautam R. and Dikundwar, Amol G. and Dubey, Ritesh and Duggirala, Nagakiran and Ghogale, Preetam P. and Ghosh, Soumyajit and Goswami, Pramod Kumar and Goud, N. Rajesh and Jetti, Ram R. K. R. and Karpinski, Piotr and Kaushik, Poonam and Kumar, Dinesh and Kumar, Vineet and Moulton, Brian and Mukherjee, Arijit and Mukherjee, Gargi and Myerson, Allan S. and Puri, Vibha and Ramanan, Arunachalam and Rajamannar, T. and Reddy, C. Malla and Rodriguez-Hornedo, Nair and Rogers, Robin D. and Row, T. N. Guru and Sanphui, Palash and Shan, Ning and Shete, Ganesh and Singh, Amit and Sun, Changquan C. and Swift, Jennifer A. and Thaimattam, Ram and Thakur, Tejender S. and Thaper, Rajesh Kumar and Thomas, Sajesh P. and Tothadi, Srinu and Vangala, Venu R. and Vishweshwar, Peddy and Weyna, David R. and Zaworotko, Michael J.} } @article {46400, title = {Design and synthesis of 3D porous diamondoid frameworks by cocrystallization}, journal = {Acta Crystallographica A-Foundation and Advances}, volume = {70}, year = {2014}, month = {MAY}, pages = {C470}, type = {Meeting Abstract}, keywords = {cocrystals, crystal engineering, Porous Organic Cages}, issn = {2053-2733}, author = {Tothadi, Srinu and Little, Marc A. and Hasell, Tom and Briggs, Michel E. and Chong, Samantha Y. and Cooper, Andrew I.} } @article {46372, title = {Supramolecular synthon hierarchy in bumetanide cocrystals}, journal = {Acta Crystallographica A-Foundation and Advances}, volume = {70}, year = {2014}, month = {FEB}, pages = {C721}, type = {Meeting Abstract}, keywords = {Novel cocrystals of sulfonamide drug Bumetanide with carboxamides are developed based on supramolecular synthons approach}, issn = {2053-2733}, author = {Allu, Suryanarayana and Bolla, Geetha and Tothadi, Srinu and Nangia, Ashwini} } @article {43908, title = {Modular assembly of porous organic cage crystals: isoreticular quasiracemates and ternary co-crystal}, journal = {CrystEngComm}, volume = {19}, year = {2017}, month = {SEP}, chapter = {4933-4941}, abstract = {

Small changes in molecular structure and crystallisation conditions can have a profound effect on the crystal packing of molecules. Increasing the system complexity-for example, by introducing multiple components-greatly increases the number of potential outcomes. Hence, the rational design of porous cocrystals with multiple components is challenging. Here, we report a family of isoreticular quasiracemate crystalline phases for porous organic cages, FT-RCC3-R center dot CCX-S (where X = 1, 2, or 4), that were prepared in a modular and predictable fashion. By using directional intermolecular interactions between cages, we were able to prepare a rare ternary co-crystal, (CC3-S(0.5)CC4-S-0.5)center dot(CC13-S(0.5)CC3-S(0.25)CC4-S-0.25).

}, keywords = {cocrystals, Frameworks, Gas-chromatography, Halogen Bonds, Hydrogen-bonds, Molecular Cage, Nanoparticles, Pores, porosity, Separation}, issn = {1466-8033}, doi = {10.1039/c7ce00783c}, author = {Tothadi, Srinu and Little, Marc A and Hasell, Tom and Briggs, Michael E. and Chong, Samantha Y. and Liu, Ming and Cooper, Andrew I.} } @article {43818, title = {Supramolecular synthons in bumetanide cocrystals and ternary products}, journal = {Crystal Growth \& Design}, volume = {17}, year = {2017}, month = {AUG}, pages = {4225-4236}, type = {Article}, abstract = {A novel design strategy for cocrystals of the diuretic sulfonamide drug bumetanide (BUM) with carboxamides is reported based on reliable supramolecular synthons. Binary cocrystals of BUM with pyridine carboxamides, pyridones, and cytosine were obtained by solvent assisted grinding followed by solution crystallization. All cocrystal structures exhibit hydrogen bonding of the coformer with the carboxylic acid group of BUM via heterosynthons which replace the acid homodimer in the drug crystal structure. Pyridones are inserted as N-H center dot center dot center dot O dimers which are in turn bonded to the acid group of BUM, while the pyridine amide coformers interact via the acid amide heterosynthon. Cocrystal polymorphs were obtained for bumetanide isonicotinamide cocrystal structure with the sulfonamide pyridine and sulfonamide acid synthons. Careful crystal packing analysis of BUM structure and nine new binary adducts gave an idea for the design ternary cocrystals, and subsequently four new ternary crystalline products were crystallized. Whereas the binary cocrystal structures were confirmed by single crystal diffraction, the ternary combinations were chatacterized by their unique powder X-ray diffraction patterns as well as by thermal and spectroscopic techniques.}, doi = {10.1021/acs.cgd.7b00531}, author = {Allu, Suryanarayana and Bolla, Geetha and Tothadi, Srinu and Nangia, Ashwini} } @article {45379, title = { Systematic synthesis of a 6-component organic-salt alloy of naftopidil, and pentanary, quaternary and ternary multicomponent crystals}, journal = {IUCrJ}, volume = {5}, year = {2018}, month = {NOV}, pages = {816-822}, type = {Article}, abstract = {The single-crystal X-ray structure of a 6-component organic-salt alloy (hexanary) of naftopidil (1) (an active pharmaceutical ingredient) with benzoic acid (2) and four different hydroxy-substituted benzoic acids, i.e. salicylic acid (3), 2,3-dihydroxybenzoic acid (4), 2,4-dihydroxybenzoic acid (5) and 2,6-dihydroxybenzoic acid (6), is reported. The hexanary assembly originates from the observation that the binary salts of naftopidil with the above acids are isostructural. In addition to the 6-component solid, we also describe five 5-component, ten 4-component, and ten 3-component organic-salt alloys of naftopidil (1) with carboxylic acids (2)-(6). These alloys were obtained from different combinations of the acids with the drug. The synthetic design of the multicomponent organic alloys is based on the rationale of geometrical factors (shape and size) and chemical interactions (hydrogen bonds). The common supramolecular synthon in all these crystal structures was the cyclic N+ - H center dot center dot center dot O- and O-H center dot center dot center dot O hydrogen-bonded motif of R-2(2) (9) graph set between the 2-hydroxyammonium group of naftopidil and the carboxylate anion. This ionic synthon is strong and robust, directing the isostructural assembly of naftopidil with up to five different carboxylic acids in the crystal structure together with the lower-level multicomponent adducts. Solution crystallization by slow evaporation provided the multicomponent organic salts and alloys which were characterized by a combination of single-crystal X-ray diffraction, powder X-ray diffraction, NMR and differential scanning calorimetry techniques.}, issn = { 2052-2525}, doi = { 10.1107/S2052252518014057}, author = {Dandela, Rambabu and Tothadi, Srinu and Marelli, Udaya Kiran and Nangia, Ashwini} } @article {46129, title = {Does stoichiometry matter? cocrystals of aliphatic dicarboxylic acids with isonicotinamide: odd-even alternation in melting points}, journal = {Crystengcomm}, volume = {21}, year = {2019}, month = {APR }, pages = {2481-2484}, type = {Article}, abstract = {

{This study outlines the synthesis of four cocrystals of aliphatic dicarboxylic acids {pimelic acid to sebacic acid (HOOC-(CH2) nCOOH

}, issn = {1466-8033}, doi = {10.1039/c9ce00299e}, author = {Tothadi, Srinu and Phadkule, Amala} } @article {46162, title = {Porosity switching in polymorphic porous organic cages with exceptional chemical stability}, journal = {Angewandte Chemie-International Edition}, volume = {58}, year = {2019}, month = {MAR}, pages = {4243-4247}, type = {Article}, abstract = {

Porous solids that can be switched between different forms with distinct physical properties are appealing candidates for separation, catalysis, and host-guest chemistry. In this regard, porous organic cages (POCs) are of profound interest because of their solution-state accessibility. However, the application of POCs is limited by poor chemical stability. Synthesis of an exceptionally stable imine-linked (4+6) porous organic cage (TpOMe-CDA) is reported using 2,4,6-trimethoxy-1,3,5-triformyl benzene (TpOMe) as a precursor aldehyde. Introduction of the -OMe functional group to the aldehyde creates significant steric and hydrophobic characteristics in the environment around the imine bonds that protects the cage molecules from hydrolysis in the presence of acids or bases. The electronic effect of the -OMe group also plays an important role in enhancing the stability of the reported POCs. As a consequence, TpOMe-CDA reveals exceptional chemical stability in neutral, acidic and basic conditions, even in 12m NaOH. Interestingly, TpOMe-CDA exists in three different porous and non-porous polymorphic forms (, , and ) with respect to differences in crystallographic packing and the orientation of the flexible methoxy groups. All of the polymorphs retain their crystallinity even after treatment with acids and bases. All the polymorphs of TpOMe-CDA differ significantly in their properties as well as morphology and could be reversibly switched in the presence of an external stimulus.

}, keywords = {chemical stability, Morphology, organic cages, polymorphism, porosity switching}, issn = {1433-7851}, doi = {10.1002/anie.201813773}, author = {Bera, Saibal and Dey, Kaushik and Pal, Tapan K. and Halder, Arjun and Tothadi, Srinu and Karak, Suvendu and Addicoat, Matthew and Banerjee, Rahul} } @article {46425, title = {Saturated N-heterocyclic carbene based thiele{\textquoteright}s hydrocarbon with a tetrafluorophenylene linker}, journal = {Chemistry-A European Journal}, year = {2019}, month = {NOV}, type = {Article; Early Access}, abstract = {

The synthesis of a SIPr [1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene] derived Kekule diradicaloid with a tetrafluorophenylene spacer (3) has been described. Two synthetic routes have been reported to access 3. The cleavage of C-F bond of C6F6 by SIPr in the presence of BF3 led to double C-F activated compound with two tetrafluoro borate counter anions (2), which upon reduction by lithium metal afforded 3. Alternatively, 3 can be directly accessed in one step by reacting SIPr with C6F6 in presence of Mg metal. Compounds 2 and 3 were well characterized spectroscopically and by single-crystal X-ray diffraction studies. Experimental and computational studies support the cumulenic closed-shell singlet state of 3 with a singlet-triplet energy gap (Delta ES-T) of 23.7 kcal mol(-1).

}, keywords = {C-F activation, Density functional calculations, fluorine, Kekule diradicaloids, saturated NHC}, issn = {0947-6539}, doi = {10.1002/chem.201904421}, author = {Kundu, Gargi and De, Sriman and Tothadi, Srinu and Das, Abhishek and Koley, Debasis and Sen, Sakya S.} } @article {46606, title = {Bis(silanetellurone) with C-H center dot center dot center dot Te Interaction}, journal = {Inorganic Chemistry}, volume = {59}, year = {2020}, month = {DEC }, pages = {17811-17821}, type = {Article}, abstract = {

Herein, we report the synthesis of a series of bis(silanechalcogenones) [Ch = Te (2), S (3), or Se (4)] using an N-heterocyclic silylene-based SiCSi pincer ligand (1). 2 is the first example of a bis(silanetellurone) derivative. The bonding patterns of 2-4 were extensively studied by natural bond orbital, quantum theory of atoms in molecules, and noncovalent interaction index analyses, and these exhibit weak C-H center dot center dot center dot Ch interaction. The analogous reaction of 1 with trimethyl N-oxide produced a novel bis(cyclosiloxane) derivative (5). All of the complexes are duly characterized by single-crystal X-ray diffraction studies, multinuclear nuclear magnetic resonance (H-1, C-13, and Si-29) spectroscopy, and high-resolution mass spectrometry.

}, issn = {0020-1669}, doi = {10.1021/acs.inorgchem.0c03098}, author = {Ghosh, Moushakhi and Panwaria, Prakash and Tothadi, Srinu and Das, Aloke and Khan, Shabana} } @article {46904, title = {Morphological evolution of two-dimensional porous hexagonal trimesic acid framework}, journal = {ACS Applied Materials \& Interfaces}, volume = {12}, year = {2020}, month = {APR }, pages = {15588-15594}, type = {Article}, abstract = {

Hexagonal single crystal structure (Form II) of trimesic acid (TMA) has been isolated by dissolving the interpenetrated Form I of TMA in tetrahydrofuran. Form II (hexagonal) was converted to Form I (interpenetrated) at room temperature through some intermediate structures. A detailed time-dependent FESEM study shows that the external morphology of Form II (hexagonal) is a hollow hexagonal tube that mimics its crystal structure. The block-shaped (morphology) of Form I (interpenetrated) was converted to the hollow hexagonal tube through some intermediate morphologies which are corresponding to particular crystal structures. Here, we have established a strong correlation between crystal structures with the morphology. These hollow tubes have been employed for Rhodamine B dye adsorption studies and showed an uptake of 82\%, much more significant than Form I (interpenetrated) (39\%) due to the presence of a pore channel in the crystal structure.

}, keywords = {dye adsorption, hollow hexagonal rod, hydrogen-bonded organic framework, morphology evaluation, trimesic acid}, issn = {1944-8244}, doi = {10.1021/acsami.0c01398}, author = {Tothadi, Srinu and Koner, Kalipada and Dey, Kaushik and Addicoat, Matthew and Banerjee, Rahul} } @article {46868, title = {Naftopidil molecular salts with improved dissolution and permeation}, journal = {Crystal Growth \& Design}, volume = {20}, year = {2020}, month = {MAY }, pages = {3064-3076}, type = {Article}, abstract = {

Naftopidil (NFPD) is a alpha 1 adrenoceptor antagonist drug. Low solubility and low permeability are the major drawbacks of this drug. The synthesis of multicomponent crystalline forms of this amine functional group drug with carboxylic acid coformers, both achiral and chiral acids, provides a solution to improve its solubility as well as permeability. Nine molecular salts were crystallized by liquid-assisted grinding followed by isothermal crystallization. Single-crystal X-ray diffraction analysis of the molecular salts showed that the structures are stabilized by strong N-H center dot center dot center dot O and O-H center dot center dot center dot O and weak C-H center dot center dot center dot O hydrogen bonds in the solid state. The bulk phase purity of new solid forms was confirmed by powder X-ray diffraction (PXRD), and the crystalline products were further characterized by IR spectroscopy and thermal analytical techniques (differential scanning calorimetry). The molecular salts exhibit superior dissolution rates compared to pure NFPD. However, during dissolution, NFPD showed decrease in concentration after 60 min for all salts due to precipitation. The supersaturation occurred due to salt disproportionation, which generates insoluble NFPD, as confirmed by PXRD of the residue. The salts reach high saturation concentration before 60 min, which is indicative of immediate release formulation to achieve fast onset of therapeutic activity. Moreover, the salts exhibit high saturation in phosphate buffer saline media and improved permeability compared to the pure drug. Finally, the D,L-malic acid racemate of NFPD shows enhanced dissolution and permeability compared to all other salts and pure NFPD.

}, issn = {1528-7483}, doi = {10.1021/acs.cgd.9b01689}, author = {Mannava, M. K. Chaitanya and Dandela, Rambabu and Tothadi, Srinu and Solomon, K. Anand and Nangia, Ashwini K.} } @article {46974, title = {Novel pharmaceutical cocrystals and salts of bumetanide}, journal = {Crystal Growth \& Design}, volume = {20}, year = {2020}, month = {FEB}, pages = {793-803}, type = {Article}, abstract = {

New crystalline forms of bumetanide, namely, four cocrystals, two salts, and one salt-cocrystal were crystallized. Urea and lactams such as valerolactam, caprolactam, and N-methyl caprolactam formed cocrystals with bumetanide, whereas 4-aminopyridine gave a salt. Piperazine afforded a salt hydrate, and 5-fluorocytosine gave a salt-cocrystal. The supramolecular synthons in bumetanide-lactam cocrystals are an amide dimer between drug and coformer, and acid homo dimer between bumetanide molecules. In bumetanide salts, the acid proton is transferred from bumetanide to coformer amine, whereas in bumetanide salt-cocrystal proton transfer and free acid were observed in the crystal structure. Similarly, the cytosine salt-cocrystal of bumetanide and fluorocytosine also gave a salt-cocrystal adduct. The acid proton of bumetanide is transferred to the 2-amino pyridine base of cytosine as a salt, and on the other side of the drug molecule the sulfonamide interacts with the syn amide part of cytosine. Furthermore, solubility, dissolution, and diffusion membrane permeability experiments were performed on all new solid forms. The piperazine salt shows high dissolution and permeability crossover when compared to other binary forms of bumetanide.

}, issn = {1528-7483}, doi = {10.1021/acs.cgd.9b01195}, author = {Allu, Suryanarayana and Bolla, Geetha and Tothadi, Srinu and Nangia, Ashwini K.} } @article {46599, title = {Stepwise nucleophilic substitution to access saturated N-heterocyclic carbene haloboranes with boron-methyl bonds}, journal = {Organometallics}, volume = {39}, year = {2020}, month = {DEC}, pages = {4696-4703}, type = {Article}, abstract = {

Compounds of boranes with N-heterocyclic carbenes are known, yet little attention has been paid to NHC compounds of boron bearing methyl and halogen moieties together. The reason can be attributed to the hazardous methyldichloroborane (MeBCl2), which ignites in air. We describe here convenient solution-phase access to SIDipp.MeBCl2 (SIDipp = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) (3) by a salt metathesis reaction of SIDipp.BCl3 (2) with MeLi. Replacement of the chlorine atoms of 3 with stepwise addition of AgOTf led to the formation of SIDipp.MeBCl(OTf) (4) and SIDipp.MeB(OTf)2 (5). In the case of 4, all of the substituents on the boron atom are different. Subsequently, we extended our synthetic approach to the amidinate system and prepared PhC(NtBu)2B(Me)Cl (7) from the reaction of PhC(NtBu)2BCl2 (6) with MeLi.

}, issn = {0276-7333}, doi = {10.1021/acs.organomet.0c00691}, author = {Kundu, Gargi and Pahar, Sanjukta and Tothadi, Srinu and Sen, Sakya S.} } @article {47084, title = {Can we identify the salt-cocrystal continuum state using XPS?}, journal = {Crystal Growth \& Design}, volume = {21}, year = {2021}, month = {FEB }, pages = {735-747}, type = {Article}, abstract = {

X-ray photoelectron spectroscopy (XPS) is used to understand the nature of acid-base crystalline solids, to know whether the product is a salt (proton transfer, O-center dot center dot center dot H-N+) or a cocrystal (neutral adduct, O-H center dot center dot center dot N). The present study was carried out to explore if intermediate states of proton transfer from COOH to nitrogen (the proton resides between hydrogen bonded to O and N, O center dot center dot center dot H center dot center dot center dot N, quasi state) can be differentiated from a salt (complete proton transfer, N+-H center dot center dot center dot center dot O-) and cocrystal (no proton transfer, O-H center dot center dot center dot N) using N 1s XPS spectroscopy. The intermediate states of proton transfer arise when the pK(a) difference between the acid and the conjugate base is between -1 and 4, -1 \< Delta pK(a) \< 4, a situation common with COOH and pyridine functional groups present in drug molecules and pharmaceutically acceptable coformers. Complexes of pyridine N bases with aromatic COOH molecules in nine salts/cocrystals were cocrystallized, and their N 1s core binding energies in XPS spectra were measured. The proton state was analyzed by single-crystal X-ray diffraction for confirmation. Three new complexes were crystallized and analyzed by XPS spectra (without knowledge of their X-ray structures), to assess the predictive ability of XPS spectra in differentiating salt-cocrystal intermediate states against the extremities. The XPS results were subsequently confirmed by single-crystal X-ray data. Complexes of 3,5-dinitrobenzoic acid and isonicotinamide in 1:1 and 1:2 ratios exist as a salt and a salt-cocrystal continuum, respectively, as shown by the N 1s core binding energies. The proton states of the crystalline solids by XPS are in good agreement with the corresponding crystal structures. Other complexes, such as those of 3,5-dinitrobenzoic acid with 1,2-bis(4-pyridyl)ethylene, exhibit a salt-cocrystal continuum, maleic acids with 1,2-bis(4-pyridyl)ethylene and acridine are salts, 2-hydroxybenzoic acid and acridine is a salt, and the complex of 3,5-dinitrobenzoic acid and 3-hydroxypyridine is a salt and salt-cocrystal continuum, while fumaric acids with 1,2-bis(4-pyridyl)ethylene and acridine are cocrystals. Furthermore, three new acidbase complexes of 3,5-dinitrobenzoic acid with phenazine, 4-hydroxypyridine, and 4-cyanopyridine were studied initially by XPS and then confirmed by X-ray diffraction. In summary, since the N 1s binding energies cluster in a narrow range as cocrystals (398.7-398.9 eV) and salts (400.1-401.1 eV), it is clearly possible to differentiate between cocrystals and salts, but the saltcocrystal continuum values in XPS spectra are clustered in an intermediate range of cocrystals and salts but overlap with those of cocrystal or salt binding energies.

}, issn = {1528-7483}, doi = {10.1021/acs.cgd.0c00661}, author = {Tothadi, Srinu and Shaikh, Tabrez Rafique and Gupta, Sharad and Dandela, Rambabu and Vinod, Chathakudath P. and Nangia, Ashwini K.} } @article {47645, title = {Carbazole substituted amidinato silylene: synthesis, bonding, and coordination behavior with coinage metals}, journal = {Organometallics}, volume = {40}, year = {2021}, month = {SEP}, pages = {3201-3210}, type = {Article}, abstract = {In this work, the synthesis and characterization of a new carbazole substituted amidinatosilylene (1) and its coinage metal complexes 3-8 are being reported. Before the complexation reactions, we prepared [PhC(N+Bu)(2)Si(Cbz)-> Co(CO)Cp] complex (2) to estimate the sigma-donating strength of the newly synthesized silylene 1. Further, several commonly available coinage metal salts were utilized for the complexation reactions with 1, which afforded complexes 3-8. The solid-state structures of 1-8 have been validated by single-crystal X-ray diffraction studies, NMR spectroscopy, and mass spectroscopy. DFT studies were also performed to understand the bonding scenario of 1 and 3-7. Of note, 1 consists of a HOMO on its carbazolide moiety, and the HOMO-1 features the silylene character. We also compared the HOMO-LUMO gap of 1 with other amidinato silylenes having different N-substitutions.}, issn = {0276-7333}, doi = {10.1021/acs.organomet.1c00399}, author = {Ghosh, Moushakhi and Tothadi, Srinu and Khan, Shabana} } @article {47422, title = {Diverse reactivity of carbenes and silylenes towards fluoropyridines}, journal = {Chemical Communications}, volume = {57}, year = {2021}, month = {MAY }, pages = {4428-4431}, type = {Article}, abstract = {

The reaction of IDipp with C5F5N led to functionalization of all three carbon atoms of the imidazole ring with HF2- as the counter-anion (1). Reactivity with 2,3,5,6-tetrafluoropyridine gives only C-F bond activation leaving C-H bonds intact (5b). The reaction of SIDipp with C5F5N in the presence of BF3 afforded the ring cleavage product (3). Analogous reactions with silylene led to oxidative addition at the Si(II) center.

}, issn = {1359-7345}, doi = {10.1039/d1cc01401c, Early Access Date = MAR 2021}, author = {Kundu, Gargi and Ajithkumar, V. S. and Bisai, Milan Kumar and Tothadi, Srinu and Das, Tamal and Vanka, Kumar and Sen, Sakya S.} } @article {47379, title = {Diverse reactivity of NOBF4 towards silylene, disilene, germylene and stannylene}, journal = {Chemical Communications}, volume = {57}, year = {2021}, month = {MAY}, pages = {5008-5011}, type = {Article}, abstract = {

{The reactivity of NOBF4 towards silylene, disilene, germylene, stannylenes has been described. Smooth syntheses of compounds of composition [PhC(NtBu)(2)E(= O -\> BF3)N(SiMe3)(2)

}, issn = {1359-7345}, doi = {10.1039/d1cc01034d, Early Access Date = APR 2021}, author = {Parvin, Nasrina and Sen, Nilanjana and Muhasina, Puthan Veetil and Tothadi, Srinu and Parameswaran, Pattiyil and Khan, Shabana} } @article {47655, title = {Pyridylpyrrolido ligand in Ge(II) and Sn(II) chemistry: synthesis, reactivity and catalytic application}, journal = {Dalton Transactions}, volume = {50}, year = {2021}, month = {NOV}, pages = {16678-16684}, type = {Article}, abstract = {In our previous communication, we have reported the synthesis of a new chlorogermylene (B) featuring a pyridylpyrrolido ligand. This study details the preparation of a series of new germylenes and stannylenes starting from B. A transmetallation reaction between B and SnCl2 led to the analogous chlorostannylene (1) with the simultaneous elimination of GeCl2. This is a very unusual example of transmetallation between two elements of the same group. The preparation of 1via lithiation led to the formation of 2 as a side product, where the ortho C-H bond of the pyridine ring was activated and functionalized with a Bu-n moiety. Subsequently, B and 1 were used as precursors to generate germylene (4) and stannylene (5) featuring tris(trimethylsilyl)silyl (hypersilyl) moieties. We also prepared tetrafluoropyridyl germylene (6) by reacting 4 with C5F5N with the simultaneous elimination of (Me3Si)(3)SiF by utilizing the fluoride affinity of the silicon atom. As there is scarcity of Sn(II) compounds as single-site catalysts, we investigated 5 as a catalyst towards the hydroboration of aldehydes, ketones, alkenes and alkynes. All the compounds have been characterized by single-crystal X-ray diffraction and by state of the art spectroscopic studies.}, issn = {1477-9226}, doi = {10.1039/d1dt03136h}, author = {Pahar, Sanjukta and Sharma, Vishal and Tothadi, Srinu and Sen, Sakya S.} } @article {47618, title = {Reactivity of (TMS)(2)N(eta(1)-Cp*)Si=Si(eta(1)-Cp*)N(TMS)(2) toward the Halides of Groups 13-15}, journal = {Organometallics}, volume = {40}, year = {2021}, month = {JUN }, pages = {1874-1883}, type = {Article}, abstract = {In this paper, we have demonstrated the unique reactivity of a previously reported disilene [(TMS)(2)N(eta(1)-Me5C5)Si=Si(eta(1)-Me5C5)N(TMS)(2)] (1) with the halides of groups 13-15, which resulted in the formation of silicon-E (E = B, Al, Ge, P) bonds. Treatment of 1 with Lewis acidic BCl3 led to the formation of a cationic boron species [Cp*BSi(Cl)(2)N(TMS)(2))][BCl3SiCl3] (2). In contrast, the reaction of 1 with BCy2Cl afforded an oxidative addition product [(TMS)(2)N(eta(1)-Me5C5)Si(BCy2)(Cl)] (3) via the insertion of a Si(II) atom into the B-Cl bond. Extending the reaction with its higher congener led to classical Lewis acid-base adducts, (TMS)(2)N(eta(1)-Me5C5)Si -> AlCl3 (4) and (TMS)(2)N(eta(1)-Me5C5)Si -> AlBr3 (5), respectively. The reaction of GeCl2 with 1 proceeded in a completely different manner and resulted in a hybrid dendrimeric compound [HGe(Si(Cl)(2)N(TMS)(2))(3)] (6), whereas, with SnCl2, it led to Cp*SnCl (7). Lastly, the reaction of Ph2PCl followed the same pattern like Cy2BCl and led to the formation of an oxidative addition product [(TMS)(2)N(eta(1)-Me5C5)Si(PPh2)(Cl)] (9) with a Si-P bond.}, issn = {0276-7333}, doi = {10.1021/acs.organomet.1c00203}, author = {Sen, Nilanjana and Parvin, Nasrina and Tothadi, Srinu and Khan, Shabana} } @article {47691, title = {Separation of a diastereomeric diol pair using the mechanical properties of crystals}, journal = {Crystengcomm}, volume = {23}, year = {2021}, month = {OCT}, pages = {7056-7060}, type = {Article}, abstract = {We report the separation of a (2S,3R/S)-3-ethyl-1-phenylhex-5-ene-2,3-diol (ephd) diastereomeric pair with visually indistinguishable acicular morphologies based on their mechanical responses, which is found to be more efficient than conventional separation methods. Furthermore, the molecular crystals of (2S,3R)-ephd show elastic deformation, while (2S,3S)-ephd fractures in a brittle manner under similar conditions.}, doi = {10.1039/d1ce01055g}, author = {Gamidi, Rama Krishna and Dandawate, Monica and Choudhury, Rahul and Tothadi, Srinu and Nangia, Ashwini and Reddy, D. Srinivasa} } @article {47693, title = {Structure-property correlation of halogen substituted benzothiazole crystals}, journal = {Journal of Molecular Structure}, volume = {1243}, year = {2021}, month = {NOV }, pages = {130765}, type = {Article}, abstract = {We have synthesized 3 benzothiazole crystals (1-3) based on existing knowledge of combining flexibility and optical properties towards achieving applications for flexible optoelectronics. However, one crystal was found to be elastically bendable and was found to comply necessary packing features for elasticity. Other two crystals do not obey packing features for elasticity hence they are brittle in nature. Further, Hirshfeld analysis illustrates that elastic crystal 1 possess more number of weak and dispersive interactions compared to other crystals. These interactions were instrumental in invoking elasticity. Moreover, crystals 1-3 were found to be fluorescent as well at specific excitation wavelengths. Therefore, among these crystals, particularly crystal 1 is considered as more promising candidate for flexible optoelectronics. (C) 2021 Elsevier B.V. All rights reserved.}, keywords = {Benzothiazole crystals, Elasticity, Halogen bond, mechanical properties}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2021.130765}, author = {Thekkeppat, Nipun P. and Singla, Labhini and Tothadi, Srinu and Das, Priyadip and Choudhury, Angshuman Roy and Ghosh, Soumyajit} } @article {47724, title = {Synthesis and application of silylene-stabilized low-coordinate Ag(I)-arene cationic complexes}, journal = {Organometallics}, volume = {40}, year = {2021}, month = {JUN }, pages = {1626-1632}, type = {Article}, abstract = {We report the first examples of N-heterocyclic silylene-stabilized monocoordinate Ag(I) cationic complexes weakly bound to the free arene rings (C6H6, C6Me6, and C7H8). Further, the application of these electrophilic Ag(I) complexes as catalysts has been investigated toward A(3)-coupling reactions, which afforded a series of propargylamines in good to excellent yields with low catalyst loading under a solvent-free condition (19 examples).}, issn = {0276-7333}, doi = {10.1021/acs.organomet.1c00083}, author = {Parvin, Nasrina and Sen, Nilanjana and Tothadi, Srinu and Muhammed, Shahila and Parameswaran, Pattiyil and Khan, Shabana} } @article {47690, title = {Three in one: triple G-C-T base-coded brahma nucleobase amino acid: synthesis, peptide formation, and structural features}, journal = {Journal of Organic Chemistry}, volume = {86}, year = {2021}, month = {NOV }, pages = {15689-15694}, type = {Article}, abstract = {This note reports the synthesis and peptide formation of a novel triple G-C-T nucleobase amino acid (NBA) building block featuring three recognition faces: DDA (G mimic), DAA (C mimic), and ADA (T mimic). Readily obtainable in multigram scale in a remarkably easy one-step reaction, this unique NBA building block offers scope for wide ranging applications for nucleic acid recognition and nucleic acid peptide/protein interaction studies.}, issn = {0022-3263}, doi = {10.1021/acs.joc.1c01228}, author = {Wagh, Mahendra A. and Maity, Rahul and Bhosale, Rohit J. and Semwal, Divyam and Tothadi, Srinu and Vaidhyanathan, Ramanathan and Sanjayan, Gangadhar J.} } @article {47064, title = {Triazine-based janus G-C nucleobase as a building block for self-assembly, peptide nucleic acids, and smart polymers}, journal = {Journal of Organic Chemistry}, volume = {86}, year = {2021}, month = {FEB }, pages = {3186-3195}, type = {Article}, abstract = {

This communication reports on the utility of a triazine-based self-assembling system, reminiscent of a Janus G-C nucleobase, as a building block for developing (1) supramolecular polymers, (2) peptide nucleic acids (PNAs), and (3) smart polymers. The strategically positioned self-complementary triple H-bonding arrays DDA and AAD facilitate efficient self-assembly, leading to a linear supramolecular polymer.

}, issn = {0022-3263}, doi = {10.1021/acs.joc.0c02530}, author = {Meena, Chhuttan L. and Singh, Dharmendra and Kizhakeetil, Bhavya and Prasad, Manasa and George, Malini and Tothadi, Srinu and Sanjayan, Gangadhar J.} } @article {47764, title = {Different mechanical responses of dimorphic forms of anthracene schiffbase crystal}, journal = {Journal of Molecular Structure}, volume = {1252}, year = {2022}, month = {MAR}, pages = {132182}, type = {Article}, abstract = {We obtained concomitant dimorphic forms of Anthracene Schiffbase (N-(anthracen-9-yl methylene)-2,5dichloroaniline) from hexane solvent. Two polymorphs can be differentiated by their morphology and mechanical properties. One form is long acicular type and elastically bendable while another form is block shaped and brittle in nature. Mechanical property is attributed to underlying crystal packing. Hirshfeld analysis and energy framework calculations were done to corroborate structure-property correlation of two forms (C) 2021 Elsevier B.V. All rights reserved.}, keywords = {Anthracene schiffbase, Dimorphs, Elasticity, mechanical properties}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2021.132182}, author = {Lakshmipathi, Madhumathi and Tothadi, Srinu and Emmerling, Franziska and Bhattacharya, Biswajit and Ghosh, Soumyajit} } @article {48215, title = {First-row transition metal complexes of a phosphine-silylene- based hybrid ligand}, journal = {Inorganic Chemistry}, volume = {61}, year = {2022}, month = {AUG}, pages = {13330-13341}, type = {Article}, abstract = {

We have prepared two new silylene-phosphine-based hybrid ligands Si{N(R)C6H4(PPh2)}{PhC((NBu)-Bu-t)(2)} [R = TMS {trimethylsilyl} (1) and TBDMS {tert-butyldimethylsilyl} (2)], which possess two donor sites. Furthermore, the treatment of the bidentate ligand 1 with base metal halides {FeBr2, CoBr2, NiCl(2)middotdme [nickel chloride(II) ethylene glycol dimethyl ether]} and 2 with NiBr(2)middotdme [nickel bromide(II) ethylene glycol dimethyl ether] afforded four-coordinate six-membered metal complexes 3-6, respectively, which feature coordination from both Si(II) and P(III) sites. Subsequently, complexes 3 [(FeBr2)Si{N(SiMe3)C6H4(PPh2)}{PhC((NBu)-Bu-t)(2)}], 4 [(CoBr2)Si{N(SiMe3)C6H4(PPh2)}{PhC((NBu)-Bu-t)(2)}], 5 [(NiCl2)Si{N(SiMe3)C6H4(PPh2)}{PhC((NBu)-Bu-t)(2)}], and 6 [(NiBr2)Si{N((SiBuMe2)-Bu-t)C6H4(PPh2)}{PhC((NBu)-Bu-t)(2)}] are studied for their redox and magnetic properties with the help of UV-vis spectroscopy, cyclic voltammetry, SQUID magnetometry, and theoretical calculations. Complexes 3-6 were found to display a paramagnetic behavior. All the compounds are well established by single-crystal X-ray diffraction studies.

}, issn = {0020-1669}, doi = {10.1021/acs.inorgchem.2c01233}, author = {Akhtar, Ruksana and Kaulage, Sandeep H. and Sangole, Mayur P. and Tothadi, Srinu and Parvathy, Parameswaran and Parameswaran, Pattiyil and Singh, Kirandeep and Khan, Shabana} } @article {48142, title = {Nucleophilic substitution at a coordinatively saturated five-membered NHC center dot haloborane centre}, journal = {Inorganics}, volume = {10}, year = {2022}, month = {JUL}, pages = {97}, type = {Article}, abstract = {

In this paper, we have used a saturated five-membered N-Heterocyclic carbene (5SIDipp = 1,3-bis-(2,6-diisopropylphenyl)imidazolin-2-ylidine) for the synthesis of SNHC-haloboranes adducts and their further nucleophilic substitutions to put unusual functional groups at the central boron atom. The reaction of 5-SIDipp with RBCl2 yields Lewis-base adducts, 5-SIDipp center dot RBCl2 [R = H (1), Ph (2)]. The hydrolysis of 1 gives the NHC stabilized boric acid, 5-SIDipp center dot B(OH)(3) (3), selectively. Replacement of chlorine atoms from 1 and 2 with one equivalent of AgOTf led to the formation of 5-SIDipp center dot HBCl(OTf) (4) and 5-SIDipp center dot PhBCl(OTf) (5a), where all the substituents on the boron atoms are different. The addition of two equivalents of AgNO3 to 2 leads to the formation of rare di-nitro substituted 5-SIDipp center dot BPh(NO3)(2) (6). Further, the reaction of 5-SIDipp with B(C6F5)(3) in tetrahydrofuran and diethyl ether shows a frustrated Lewis pair type small molecule activated products, 7 and 8.

}, keywords = {NHC-haloboranes, nucleophilic substitution, saturated NHC, tetra-coordinate boron}, doi = {10.3390/inorganics10070097}, author = {Kundu, Gargi and Tothadi, Srinu and Sen, Sakya S.} } @article {48126, title = {Six-membered saturated NHC-stabilized borenium cations: isolation of a cationic analogue of borinic acid}, journal = {Inorganic Chemistry}, volume = {61}, year = {2022}, month = {AUG}, pages = {12991-12997}, type = {Article}, abstract = {

The reaction of six-membered saturated NHC [1,3-di(2,6-diisopropylphenyl) tetrahydropyrimidine-2-ylidene; henceforth abbreviated as 6-SIDipp] with PhBCl2 yields a Lewis base adduct, 6-SIDipp.PhBCl2 (1), which readily undergoes nucleophilic substitution reaction with AgNO3, leading to the single (2) and double (3) substitution of both chlorides with ONO2 moieties at the boron atom. The reaction of 1 with 1 equiv of AlCl3 resulted in a borenium cation of composition [6-SIDipp.B(Ph)Cl]+ (4) with AlCl4- as the counteranion. Although borenium cations with different substituents on boron have been reported, a structurally characterized phenylchloroborenium cation remains unknown. Similarly, the reaction of 1 with triflic acid provides the first representative of a new class of borenium cations bearing one hydroxyl and one phenyl group on boron (5), a cationic analogue of borinic acid. Ph-BN H Diphenylborinic acid

}, issn = {0020-1669}, doi = {10.1021/acs.inorgchem.2c00611}, author = {Kundu, Gargi and Balayan, Kajal and Tothadi, Srinu and Sen, Sakya S.} } @article {48149, title = {Substitution at sp(3) boron of a six-membered NHC center dot BH3: convenient access to a dihydroxyborenium cation}, journal = {Chemical Communications}, volume = {58}, year = {2022}, month = {MAR }, pages = {3783-3786}, type = {Article}, abstract = {

Herein, we have undertaken the synthesis and investigated the reactivity of a 6-membered saturated NHC borane adduct (1). Direct electrophilic halogenation of 1 with a stoichiometric amount of I-2 led to NHC boryl iodides, 6-SIDipp center dot BH2I (2) and 6-SIDipp center dot BHI2 (3), which were further reacted with various nucleophiles to give novel 6-SIDipp based mono and disubstituted boranes with OTf (4 and 6) or ONO2 (5 and 7) functional groups. The addition of Br-2/H2O to 1 smoothly results in a dihydroxyborenium cation (8).

}, issn = {1359-7345}, doi = {10.1039/d1cc06816d}, author = {Kundu, Gargi and Ajithkumar, V. S. and Raj, K. Vipin and Vanka, Kumar and Tothadi, Srinu and Sen, Sakya S.} } @article {48162, title = {Versatile chemistry of six-membered NHC with boranes: bromination at sp(3) borane, activation of the B-H bond of HBpin, and ring expansion of NHC}, journal = {Dalton Transactions}, volume = {51}, year = {2022}, month = {OCT}, pages = {14452-14457}, type = {Article}, abstract = {

The NHC.borane chemistry has been majorly restricted to imidazol-2-ylidene classes of carbenes. In our previous communication, we reported the synthesis of 6-SIDipp center dot BH3 [6-SIDipp = 1,3-di(2,6-diisopropylphenyl) tetrahydropyrimidine-2-ylidene] and its electrophilic substitution reaction with iodine. Here, we have shown selective bromination of a 6-SIDipp stabilized sp(3) B-H bond. Treatment of 1.2 equivalents of N-bromosuccinamide with 6-SIDipp center dot BH3 gives a mixture of mono- and disubstituted products 6-SIDipp center dot BH2Br (1) and 6-SIDipp center dot BHBr2 (2). However, the reactions with alkyl bromides or carbon tetrabromide resulted in 6-SIDipp center dot BH2Br (1) selectively. Exploration of the chemistry of 6-SIDipp with BHCl2 and 9-BBN (9-borabicyclo[3.3.1]nonane) led to mono-6-SIDipp adducts 3 and 6a. Furthermore, 6a undergoes ring expansion to afford a seven-membered product, 6b, under mild conditions. Unlike BHCl2 or 9-BBN, the B-H bond of HBpin undergoes oxidative addition upon reaction with 6-SIDipp, epitomizing the first example (7) of a B-H bond insertion at NHCs. The analogous reactivity with HBcat led to a tetra-hydropyrimidinium salt with B(cat)(2) as a counteranion (8).

}, issn = {1477-9226}, doi = {10.1039/d2dt01707e}, author = {Kundu, Gargi and Dixit, Ruchi and Tothadi, Srinu and Vanka, Kumar and Sen, Sakya S.} } @article {48753, title = {Activation of the olefinic C-H bond of NHC and NHO by perimidine-based silicon and germanium compounds}, journal = {Organometallics}, volume = {42}, year = {2023}, month = {JUL}, pages = {1909-1917}, type = {Article}, abstract = {

In this manuscript, several backbonegermylene-functionalized zwitterioniccompounds were prepared conveniently from the corresponding N-heterocycliccarbenes or N-heterocyclic olefins in a single step through backboneC-H activation. Our initial motivation was to generate a silylenefrom C10H6(Me3SiN)(2)SiHCl(2) using ItBu [ItBu= (1,3-ditert-butyl)imidazol-2-ylidene], but instead, the reactionled to deprotonation from the imidazolium backbone of ItBu, forming the imidazolium salt with a silyl backbone at the C4position (3). We presumed that the reaction proceededthrough the generation of an ephemeral silylene. We subsequently preparedthe analogous germylene (4) and reacted it with IDipp[IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene], ItBu, and IDipp=CH2. Spectroscopic and crystallographicanalysis of these complexes revealed that, in all cases, there wasdeprotonation from the backbone and formation of zwitterionic products(5-7). When the hydrogen in the NHCbackbone was replaced with methyl groups such as IDipp(Me) (1,3-bis(2,6-diisopropylphenyl)-4,5-dimethylimidazol-2-ylidene),simple adduct formation occurred, exemplified by the isolation ofIDipp(Me)\& BULL;Ge(NSiMe3)(2)C10H6 (8).

}, issn = {0276-7333}, doi = {10.1021/acs.organomet.3c00167}, author = {Gour, Kritika and Pramanik, Debjit and Dash, Soumya Ranjan and Tothadi, Srinu and Vanka, Kumar and Sen, Sakya S.} } @article {48921, title = {Multicomponent solvate crystals of 3,5-dinitrobenzoic acid and acetamide and CSD analysis of solvates}, journal = {ACS Omega}, volume = {8}, year = {2023}, month = {JUN }, pages = {24644-24653}, type = {Article}, abstract = {

Twelve multicomponent solvate crystals (cocrystal solvates) of 3,5-dinitrobenzoic acid and acetamide were synthesized via slow evaporation method. All crystalline materials were characterized by single-crystal X-ray diffraction. All cocrystal solvates are isostructural, and crystal packing forms continuous channels where some solvent molecules are connected via weak intermolecular interactions with 3,5dinitrobenzoic acid and acetamide. All multicomponent solvate crystals encompass amide-amide dimer homo synthons and form R22 (8) motifs. Moreover, the phase purity of solvate crystals was analyzed by powder Xray diffraction. Further, most of the cocrystal solvates were analyzed by nuclear magnetic resonance and differential scanning calorimetry. Cambridge structural database analysis categorizes solvate propensity in single-crystal structures. The importance of hydrogen bond donor/ acceptor nature, size, and shape of solvents is also discussed in the context of crystallization and crystal packing.

}, keywords = {Co-Crystals, Design, Host Guest Complex, solvent}, issn = {2470-1343}, doi = {10.1021/acsomega.3c03091}, author = {Shaikh, Tabrez Rafique and Shelke, Nikita and Tothadi, Srinu} } @article {48479, title = {Polymorph II of hydroxyurea 150 years after its first synthesis}, journal = {Crystengcomm}, volume = {25}, year = {2023}, month = {MAY}, pages = {2712-2716}, type = {Article}, abstract = {

A new polymorph of hydroxyurea (HU) was crystallized 150 years after its first synthesis. Due to its medicinal use in neoplastic diseases and sickle cell anemia, a high throughput screen of HU binary cocrystals was attempted. Instead of a cocrystal, an isoenergetic form II crystallized concomitantly with urea in methanol.

}, doi = {10.1039/d3ce00163f}, author = {Rai, Sunil K. and Tothadi, Srinu and Arhangelskis, Mihails and George, Christy P. and Gonnade, Rajesh G. and Nangia, Ashwini K.} } @article {48738, title = {Six-membered NHC stabilized monomeric zinc complexes}, journal = {European Journal of Inorganic Chemistry}, volume = {26}, year = {2023}, month = {JUL}, pages = {e202300167}, type = {Article}, abstract = {

This paper describes the rare use of a 6-membered saturated N-heterocyclic carbene (NHC) known as 1,3-di(2,6-diisopropylphenyl) tetrahydropyrimidine-2-ylidene (abbreviated as 6-SI-Dipp) as a ligand in zinc chemistry. We report on the investigation of the reactions between 6-SI-Dipp and ZnX2, which resulted in a range of new monomeric 6-SIDipp center dot ZnX2 complexes (X=Et (1), Cl (2), Br (3), and I (4)). We also prepared a new NHC zinc complex where the two substituents of the zinc atom are different, 6-SIDipp center dot Zn(Et)Br (7) through the reaction of the proligand [6-SIDippH]Br with ZnEt2. We have observed that the reactions of complex 1 with sulfur and HBpin led to the removal of the ZnEt2 moiety, resulting in the formation of a C=S double bond and a B H activation product, respectively. Lastly, the reaction of 1 with five-membered NHCs led to the exchange of carbene and the formation of either 5-IDipp center dot ZnEt2 (8) or 5-SIDipp center dot ZnEt2 (9).

}, keywords = {Lewis adduct, NHC, X-ray diffraction, zinc}, issn = {1434-1948}, doi = {10.1002/ejic.202300167}, author = {Gour, Kritika and Kundu, Gargi and Dash, Soumya Ranjan and Vanka, Kumar and Tothadi, Srinu and Sen, Sakya S.} } @article {48769, title = {Taming the parent oxoborane}, journal = {Chemical Science}, volume = {14}, year = {2023}, month = {JUN}, pages = {5894-5898}, type = {Article}, abstract = {

Despite recent advancements in the chemistry of multiply bound boron compounds, the laboratory isolation of the parent oxoborane moiety, HBO has long remained an unsolved and well-recognized challenge. The reaction of 6-SIDipp(.)BH3 [6-SIDipp = 1,3-di(2,6-diisopropylphenyl)tetrahydropyrimidine2-ylidene] with GaCl3 afforded an unusual boron-gallium 3c-2e compound (1). The addition of water to 1 resulted in the release of H-2 and the formation of a rare acid stabilized neutral parent oxoborane, LB(H)]O (2). Crystallographic and density functional theory (DFT) analyses support the presence of a terminal B=O double bond. Subsequent addition of another equivalent of water molecule led to hydrolysis of the B-H bond to the B-OH bond, but the {\textquoteleft}B=O{\textquoteright} moiety remained intact, resulting in the formation of the hydroxy oxoborane compound (3), which can be classified as a monomeric form of metaboric acid.

}, issn = {2041-6520}, doi = {10.1039/d3sc01544k}, author = {Kundu, Gargi and Amrutha, P. R. and Raj, K. Vipin and Tothadi, Srinu and Vanka, Kumar and Sen, Sakya S.} } @article {48971, title = {Access to NHC-Boryl mono- and bis-selenide and utility as mild selenium transfer reagent including to the C-F bond}, journal = {Chemistry- a european journal}, volume = {30}, year = {2024}, month = {JAN }, type = {Article}, abstract = {

Reactions of 5-SIDipp \& sdot; BH3 (5-SIDipp=1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene) (1) with diphenyldiselenide provide access to 5-SIDipp-boryl mono- (5-SIDipp \& sdot; BH2SePh) (2) and bis-selenide (5-SIDipp \& sdot; BH(SePh)2) (3). The facile cleavage of the B-Se bond makes 2 a neutral source of selenium nucleophiles in substitutions reactions with benzyl bromides, and provide access to the corresponding selenoethers. The direct transformations of one of the C(sp2)-F bonds of C5F5N and C6F5CF3 to C-Se bonds have also been achieved by the use of 2 without employing transition-metal catalysts. While it was previously established that C6F6 could undergo complete defluoroselenation under harsh conditions, we successfully achieved partial defluorination of C6F6 by employing 2 as a mild selenide transfer reagent. During the formation of C-Se bonds through the cleavage of C-F bonds, the potential by-product NHC \& sdot; BH2F undergoes ring expansion of the NHC, leading to the formation of the six-membered diaazafluoroborinane (7). Access to NHC \& sdot; boryl mono- and bis-selenides from NHC \& sdot; BH3 has been achieved. The boryl mono selenide has been demonstrated to function as a selenium transfer reagent, enabling the synthesis of selenoethers from benzyl bromide. Additionally, it can also facilitate the conversion of the challenging aromatic C-F bond to a C-Se bond, resulting in concomitant ring expansion of NHC \& sdot; haloborane.image

}, keywords = {boron, C-F Bond Activation, N-Heterocyclic carbene, Ring expansion, Selenium}, issn = {0947-6539}, doi = {10.1002/chem.202302984}, author = {Kundu, Gargi and Amrutha, P. R. and Tothadi, Srinu and Sen, Sakya S.} } @article {49374, title = {Saturated NHC-stabilized borenium, boronium, hydride-bridged boron cations, and a bora-acyl chloride}, journal = {ORGANOMETALLICS}, volume = {43}, year = {2024}, month = {JUN }, pages = {1355-1361}, keywords = {activation, BORINIUM, Chemistry}, issn = {0276-7333}, doi = {10.1021/acs.organomet.4c00139}, author = {Kundu, Gargi and Amrutha, P. R. and Tothadi, Srinu and Sen, Sakya S.} } @article {49416, title = {Synthesis, characterization, and crystal structure of 2-(2-azido-phen-yl)-3-oxo-3H-indole 1-oxide}, journal = {Acta Crystallographica Section E Crystallographic Communications}, volume = {80}, year = {2024}, month = {MAR}, pages = {310-313}, abstract = {
An attempt to explore the reactivity of the nitro group in the presence of gold catalysis in comparison to the azide group yielded intriguing results. Surprisingly, only the nitro group exhibited reactivity, ultimately giving rise to the formation of the title isatogen.
An attempt to explore the reactivity of the nitro group in the presence of gold catalysis in comparison to the azide group yielded intriguing results. Surprisingly, only the nitro group exhibited reactivity, ultimately giving rise to the formation of the title isatogen, C14H8N4O2. In the crystal structure, weak C{\textemdash}H...O hydrogen bonds and π{\textendash}π stacking inter-actions link the mol-ecules. The structure exhibits disorder of the mol-ecule.

}, doi = {https://doi.org/10.1107/S2056989024001440}, author = {Dhote, Pawan and Tothadi, Srinu and Ramana, Chepuri V. and Chopra, D.} } @article {49265, title = {Unprecedented C-F bond cleavage in perfluoronaphthalene during cobaltocene reduction}, journal = {DALTON TRANSACTIONS}, volume = {53}, year = {2024}, month = {NOV }, pages = {17789-17793}, type = {Journal Article}, issn = {1477-9226}, doi = {10.1039/d4dt02791d}, author = {Kundu, Gargi and Pramanik, Debjit and Dash, Soumya Ranjan and Kumar, Ravi and Sangole, Mayur and Tothadi, Srinu and Ghosh, Aryya and Vanka, Kumar and Singh, Kirandeep and Sen, Sakya S.} } @article {49594, title = {Resolving salt-cocrystal conundrum in multicomponent crystals by using X-ray quantum crystallography}, journal = {Journal of Physical Chemistry C}, volume = {129}, year = {2025}, month = {MAY}, pages = {9169-9178}, type = {Article}, abstract = {

The structural identity of multicomponent crystals as a salt or cocrystal is dictated by the proton transfer state between the molecular components. In pharmaceutical drugs, solid-state forms such as salts or cocrystals can have significantly distinct stability, dissolution, and solubility profiles. The accurate location of proton positions is a formidable task using conventional X-ray crystallography, as the atomic scattering factors are based on spherical electron density models. Herein, we demonstrate that the X-ray quantum crystallographic (QCr) technique of Hirshfeld Atom Refinement (HAR), based on aspherical atomic scattering factors, can be effectively employed to resolve this riddle. Our HAR models accurately located the proton positions, thus distinguishing salts, cocrystals, and continuum crystal structures, which are substantiated by the N 1s binding energies from X-ray photoelectron spectroscopy (XPS) corresponding to the base components in a series of crystals. The QCr models reveal the subtle features of electron localization and bonding around the double-well potential in the intermolecular proton-transfer regions in these crystals.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.5c00975}, author = {Sudheendranath, Athul and Tothadi, Srinu and Pradhan, Amit Kumar and Prajapati, Aditya Kumar and Nangia, Ashwini and Thomas, Sajesh P.} }