@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 {50162, title = {Reactions of saturated NHC{\textperiodcentered}boranes with electron-deficient alkynes and alkenes. borirane formation, their reactivities, and coupling of tetracyanoethylene}, journal = {Dalton Transactions}, volume = {55}, year = {2026}, month = {JUN}, pages = {8356-8365}, type = {Article}, abstract = {

In this study, we describe the reactions of five- and six-membered saturated N-heterocyclic carbene boranes (NHC \& centerdot;BH3) with electron-deficient alkenes and alkynes. Notably, both five- and six-membered saturated NHCs form boriranes upon the reaction of NHC \& centerdot;BH3 with dimethyl acetylene dicarboxylate (DMAD). However, their reactivity with HCl differs: the five-membered saturated NHC-stabilized borirane undergoes ring opening in toluene/THF, whereas the six-membered saturated NHC-stabilized borirane undergoes ring expansion, forming exclusively a boralactone irrespective of solvent. Interestingly, when acetonitrile is used as a solvent, the five-membered saturated NHC-stabilized borirane yields both ring-opening and ring-expansion products. To remove the hydrogen attached to the boron atom in boriranes, we reacted the five-membered saturated NHC-stabilized borirane with AlCl3 and B(C6F5)(3), resulting in azaborolium cation or adduct formation, respectively. Transitioning from an electron-deficient alkyne to an alkene, the reaction of six-membered saturated NHC \& centerdot;BH3 with tetracyanoethylene (TCNE) led to the unusual coupling of two TCNE molecules.

}, issn = {1477-9226}, doi = {10.1039/d6dt00852f}, author = {Amrutha, P. R. and Kundu, Gargi and Ganesh, Vemuri Lakshmi and Gonnade, Rajesh G. and Gopakumar, Gopinadhanpillai and Sen, Sakya S.} }