@article {45465, title = { Cyclometallation of a germylene ligand by concerted metalation-deprotonation of a methyl group }, journal = {Dalton Transactions }, volume = {47}, year = {2018}, month = { NOV}, pages = { 15835-15844}, type = {Article }, abstract = {The reaction of [CH{(CMe)(2,6-iPr(2)C(6)H(3)N)}(2)]GeCl with LiN(SiMe3)(2) was previously reported, which led to the formation of a hetero-fulvene type germylene, [CH{(CMe)(C?CH2)(2,6-iPr(2)C(6)H(3)N)}(2)]Ge through the deprotonation of the C-H bond from the methyl substituents. In this paper, we attempted the analogous reaction with (Dipp)NCMeCHCOMeGeCl using LiN(SiMe3)(2) which gave rise to a metathesis product, (Dipp)NCMeCHCOMeGeN(SiMe3)(2) (2). However, the reactions of 2 with [M2Cl2(-Cl)(2)((5)-Cp*)(2)] (M = Rh and Ir) resulted in cyclometallated Rh and Ir complexes through the activation of the C-H bond from the germylene ligand. The complexes were characterized by single crystal X-ray analysis, which authenticated the presence of Ge-Rh and Ge-Ir bonds. DFT studies have been performed to understand the mechanism.}, issn = {1477-9226}, doi = { 10.1039/c8dt03166e}, author = {Bakthavachalam, K. and Dutta, Sayan and Arivazhagan, C. and Raghavendra, Beesam and Haridas, Anagha and Sen, Sakya S. and Koley, Debasis and Ghosh, Sundargopal} } @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 {48141, title = {Monomeric magnesium catalyzed alkene and alkyne hydroboration}, journal = {Chemistry-A European Journal}, volume = {28}, year = {2022}, month = {OCT }, type = {Article}, abstract = {

In this work, two monomeric magnesium alkyl complexes (1 and 2) were prepared using bis(phosphino)carbazole framework and among them 1 has been used as a catalyst for hydroboration of alkenes and alkynes with pinacolborane (HBpin). A broad variety of aromatic and aliphatic alkenes and alkynes were efficiently reduced. Anti-Markovnikov regioselective hydroboration of alkenes and alkynes was achieved, which was confirmed by deuterium-labelling experiments. The work represents the first example of the use of magnesium in homogeneous catalytic hydroboration of alkene with broad substrate scope. Experimental mechanistic investigations and DFT calculations provided insights into the reaction mechanism. Finally, the hydroboration protocol was extended to terpenes.

}, keywords = {carbazole, Magnesium, monomeric complexes, phosphorous, X-ray Structure}, issn = {0947-6539}, doi = {10.1002/chem.202201896}, author = {Kumar, Rohit and Dutta, Sayan and Sharma, Vishal and Singh, Praval P. and Gonnade, Rajesh G. and Koley, Debasis and Sen, Sakya S.} } @article {49393, title = {Activation of carbon disulfide by a hypersilyl germylene}, journal = {Dalton Transactions}, volume = {53}, year = {2024}, month = {JUL}, type = {Article}, abstract = {

In this work, the insertion of CS2 into the Ge-Si bond of PhC(NtBu)2Ge-Si(SiMe3)3 (1) has been investigated, resulting in the formation of PhC(NtBu)2Ge-C( 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 S)-S-Si(SiMe3)3 (2). Interestingly, the addition of NHC to 2 allows the release of NHCCS2 with concomitant regeneration of 1. Addition of another equivalent of 1 or an analogous hypersilyl silylene, [PhC(NtBu)2Si-Si(SiMe3)3], to 2 led to the formation of compounds with a GeS (3) or a SiS (4) bond. In this work, the insertion of CS2 into the Ge-Si bond of PhC(NtBu)2Ge-Si(SiMe3)3 (1) has been investigated, resulting in the formation of PhC(NtBu)2Ge-C(S)-S-Si(SiMe3)3 (2).

}, issn = {1477-9226}, doi = {10.1039/d4dt01573h}, author = {Ajithkumar, V. S. and Khilari, Nripen and Ghanwat, Pratiksha B. and Venugopal, Geethu and Koley, Debasis and Sen, Sakya S.} } @article {49897, title = {C=C insertion over N=C=O of allyl isocyanate into the Ge-Si bond of a germylene}, journal = {European Journal of Inorganic Chemistry}, volume = {28}, year = {2025}, month = {SEP}, type = {Article}, abstract = {

Two isocyanates are reacted with the germylene, PhC(NtBu)(2)Ge-Si(SiMe3)(3) (1). Phenyl isocyanate undergoes catalytic cyclotrimerization with 1 leading to 1,3,5-triphenyl isocyanurate (2), while allyl isocyanate undergoes both cyclotrimerization and the C=C bond insertion between the Ge-Si bond. The constitution of 3 is determined by single-crystal X-ray studies. The contrasting reactivity pattern is explained by comprehensive density functional theory studies.

}, keywords = {Cyclotrimerization, Density functional theory, Germylene, Insertion, isocyanates}, issn = {1434-1948}, doi = {10.1002/ejic.202500305}, author = {Ajithkumar, V. S. and Khilari, Nripen and Ghanwat, Pratiksha B. and Koley, Debasis and Sen, Sakya S.} }