关键词: 过渡金属卡宾正离子, 构型, 分子轨道, 键解离能, 从头算

Abstract: 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.

Key words: Transition metal carbene cation, Geometry, Molecular orbital, Bond dissociation energy, Ab initio