过渡金属卡宾正离子的从头算研究

过渡金属卡宾正离子被认为是如烯烃的聚合和烷基金属的分解过程等许多反应的中间体．较为稳定的环丁烷金属离子和环戊烷金属离子已从相应酮的脱羰反应获得［１］．Ｊａｃｏｂｓｏｎ等［２］研究了ＦｅＣＨ＋２和ＣｏＣＨ＋２与烯烃和环烷烃的气相反应．Ｍｃｋｅｅ［３］在...

Ab Initio Study on Transition Metal Carbene Cations

The geometries and bonding characteristic of the first-row transition metal carbene cations MCH₂⁺ were studied by ab initio (HF/LANL2DZ). All of MCH₂⁺ are coplanar. In the closed shell structures the σ and π obitals are all doubly occupied. Therefore, they are “perfect” double bonds, but in the open shell, they are “imperfect”, because there are only three electrons in σ and π orbitals. It was mainly the π-type overlap between₂ p_x of Cand 4 p_x, 3d_xz of Mthat formed the π orbitals. The dissociation energies of C-M⁺ bond appear periodic trends from Sc to Cu. The bond dissociation energies of C-M⁺ calculated at PMP3/LANL2DZlevel are basically closed to the experimental values.