Xu Jing, Ding Yi-Hong, Andrada Diego M, Frenking Gernot
State Key Laboratory of Theoretical Computational Chemistry, Institute of Theoretical Chemistry, Jilin University Changchun (P.R. China).
Chemistry. 2014 Jul 21;20(30):9216-20. doi: 10.1002/chem.201403252. Epub 2014 Jun 4.
Quantum chemical calculations show that the N-heterocyclic carbene (NHC)-stabilized silavinylidene, NHC(tBu)→C=SiR2 is a strongly bonded complex, which has a linear arrangement of the donor and acceptor moieties. The molecule is the energetically lowest lying isomer of the NHC-stabilized R2CSi isomers and it is stable towards dimerization when R is a bulky substituent. The silavinylidene complex is the only species of the silylidene homologues NHC(tBu)→E=E'R2 (E, E' = C-Pb) which possesses a linear arrangement. The unusual bonding situation is explained in terms of donor-acceptor interactions between NHC(tBu) as σ donor and C=SiR2 in the doubly excited singlet state 3a1⇒2b2 which leads to a significantly shorter C-SiR2 bond compared with free C=SiR2 .
量子化学计算表明，N - 杂环卡宾（NHC）稳定的硅亚乙烯基，NHC(tBu)→C=SiR₂是一种强键合配合物，其供体和受体部分呈线性排列。该分子是NHC稳定的R₂CSi异构体中能量最低的异构体，当R为大位阻取代基时，它对二聚化稳定。硅亚乙烯基配合物是硅亚烷基同系物NHC(tBu)→E=E'R₂（E，E' = C - Pb）中唯一具有线性排列的物种。这种不寻常的键合情况是根据NHC(tBu)作为σ供体与处于双激发单重态3a₁⇒2b₂的C=SiR₂之间的供体 - 受体相互作用来解释的，这导致与游离的C=SiR₂相比，C - SiR₂键显著缩短。
