Computational prediction of a new class of tri-coordinate cyclic heavier carbene analogues RM(μ-R)2AlR2 (M = Ge, Sn, Pb)

Abstract

Design of stable heavier carbene analogues M(II) (M = Ge, Sn, Pb) with structural motifs different from the traditional di-coordinate analogues is extremely of interest and challengeable. In this paper, we computationally designed a novel class of tri-coordinate cyclic heavier analogues of carbenes covering a number of substituents, i.e., RM(μ-R)2AlR2 (M = Ge, Sn, Pb) 1, in which two sets of inter-molecular donor–acceptor interactions were formed between the di-coordinate carbene MR2 and the AlR3 moiety. The M-centre was found to undergo both the nucleophilic and insertion reactions, indicative of the ‘carbene’ character. We also designed c-1 starting from the known di-coordinate cyclic MR2 and AlR3 under 16 kinds of substituents [NR′2, OR′, PR′2, SR′(R′ = H, Me, iPr, Ph)]; c-1 also has favourable thermodynamic stability. After the only known cyclic tri-coordinate M(II) [M2,R4] inter-molecularly formed between two di-coordinate MR2, the presently designed new tri-coordinate cyclic heavier carbene analogues should expand the higher coordinate M(II) family and await future laboratory synthesis.