SnAl4-和PbAl4-:新型平面四配位分子

摘要

The isomerization potential energy surface of XAl-4(X = Sn, Pb) at the CCSD (T)/aug-cc-pVTZ&CEP-121G//B3LYP/6-311+G(d)&LANL2DZ level(CEP-121G and LANL2DZ for Sn, Pb only) was constructed by means of the global isomeric search method. The results show that for X = Si/Ge, the planar tetra-coordinate X structure is the global isomer. Yet, for X = Sn/Pb, in addition to the planar tetra-coordinate X isomer, a "pyramidal" structure lies almost isoenergetic. Morevoer, from X = Si/Ge to X = Sn/Pb, the potential energy surface becomes smoother. The present work not only provides new clues to the 17 valence electron rule in the planar chemistry, but demonstrates that the doping at the X-site would have significant influence on the stability of the planar tetra-coordinate structure.%通过全局结构搜索,在CCSD (T)/aug-cc-pVTZ&CEP-121 G//B3 LYP/6-311+G(d) &LANL2 DZ水平上(其中CEP-121G和LANL2DZ用于Sn和Pb原子),构建了XAl4-(X=Sn,Pb)的异构化势能面,对于X=Si,Ge体系,平面四配位X异构体明显是体系的全局极小,但对于X=Sn,Pb而言,除了平面四配位X异构体外,还存在一个几乎与其等能量但未被关注的金字塔形结构.此外,从X=Si和Ge到X=Sn和Pb,体系势能面变得更为平滑.本文不但进一步检验了平面化学中的17价电子规则,也阐明了中心原子的取代效应对平面四配位结构稳定性的重要影响.