Department of Applied Chemistry, National Chiayi University, Chiayi, 60004, Taiwan.
Dalton Trans. 2010 Oct 21;39(39):9337-46. doi: 10.1039/c0dt00112k. Epub 2010 Aug 23.
The potential energy surfaces for the cycloaddition reactions of 16 valence-electron trimetallaallene species have been studied using density functional theory (B3LYP/LANL2DZ). Seven trimetallaallene species of the form [double bond splayed left]M=M=M[double bond splayed right] with five-membered-rings where M = C, Si, Ge, Sn, and Pb, have been chosen as model reactants in this work. Also, the alkene cycloaddition has been used to study the chemical reactivities of these 16 valence-electron trimetallaallene species. The present theoretical investigations suggest that their relative reactivity increases in the order: C=C=C < Si=Si=Si < Si=Ge=Si < Ge=Si=Ge < Ge=Ge=Ge < Sn=Sn=Sn < Pb=Pb=Pb. That is, less electronegative and heavier main group atoms will lead to a smaller ΔE(st) and, in turn, will facilitate the [3 + 2] cycloaddition reactions to alkenes. Furthermore, the singlet-triplet energy splitting of the 16 valence-electron trimetallaallene species, as described in the configuration mixing model attributed to the work of Pross and Shaik, can be used as a diagnostic tool to predict their reactivities. The results obtained allow a number of predictions to be made.
采用密度泛函理论（B3LYP/LANL2DZ）研究了 16 价电子三金属烯物种环加成反应的势能面。本工作选择了[双键张开左]M=M=M[双键张开右]形式的七种五元环的五价电子三金属烯物种作为模型反应物，其中 M = C、Si、Ge、Sn 和 Pb。此外，还利用烯烃环加成反应研究了这 16 价电子三金属烯物种的化学反应活性。目前的理论研究表明，它们的相对反应活性按以下顺序增加：C=C=C < Si=Si=Si < Si=Ge=Si < Ge=Si=Ge < Ge=Ge=Ge < Sn=Sn=Sn < Pb=Pb=Pb。也就是说，电负性较小和较重的主族原子将导致更小的ΔE(st)，从而有利于与烯烃的[3+2]环加成反应。此外，根据 Pross 和 Shaik 工作中归因于构型混合模型的 singlet-triplet 能量分裂，可以将 16 价电子三金属烯物种的 singlet-triplet 能量分裂用作预测其反应活性的诊断工具。所得结果可以进行一些预测。
