Chemistry - A European Journal [LCSOM]

Abstract

The   performance   of   six   newly   synthesized benzo[h]quinoline-derived  acetonitrilo  pentamethylcyclopentadienyl iridium(III) tetrakis(3,5-bis-trifluoromethylphenyl)borate salts bearing different substituents -X (-OMe, -H, -Cl, -Br, -NO2 and –(NO2)2) on the heterochelating ligand were evaluated in the dehydro-O-silylation of   benzyl   alcohol   and   the   monohydrosilylation   of   4-methoxybenzonitrile  by  Et3SiH,  two  reactions  involving  the electrophilic activation of the Si-H bond.  The benchmark shows a direct dependence of the catalytic efficiency with the electronic effect of -X, which is confirmed by theoretical assessment of the intrinsic silylicities   of  hydridoiridium(III)-silylium  adducts  and  by  the theoretical evaluation of the propensity of hydridospecies to transfer the hydrido ligand to the activated substrate. The revisited analysis of  the  Ir-Si-H  interactions  shows  that  the  most  cohesive  bond  in hydridoiridium(III)-silylium adducts is the Ir-H one, while the Ir-Si is a weak  donor-acceptor  dative  bond.  The  Si...H  interaction  in  all  the cases  is  noncovalent  in  nature  and  dominated  by  electrostatics confirming the heterolytic cleavage of the hydrosilane’s Si-H bond in this key catalytically relevant species.

Reference

Electrophilic Si-H Activation by Acetonitrilo Benzo[h]quinoline Iridacycles: Influence of Electronic Effects in Catalysis

Masoumeh Behzadi, Chunchesh Malangi Gajendramurthy, Mélanie Boucher, Christophe Deraedt, Yann Cornaton, Lydia Karmazin, Nathalie Gruber, Philippe Bertani, and Jean-Pierre Djukic

Chemistry - A European Journal, first published 17 May 2023 - doi: https://doi.org/10.1002/chem.202300811

Contact

Jean-Pierre Djukic (team LCSOM), Institut de Chimie de Strasbourg (UMR 7177).