【摘要】 用HF/3-21G解析梯度方法研究H₂CCC:的氢氢键插入和加成反应机理,结果表明,H2CCC:的H—H插入为直接插入,取端端（end-on）接近方式;H₂加成经两步完成.第一步是2+2加成,因对称性禁阻取三中心过渡态,四中心作用发生在反应的后期,第二步是CH₃CHC:的1,2氢重排.预言气相中H—H插入容易发生,势垒值约为45 kJ/mol.更多还原

【Abstract】 Reactions H2CCC: (1)+H2→CH2CCH2(2)+CH,CCH(3) are studied using HF/3-21Ggradient method. The insertion 1+H2→2 occurs easily in fashion of "end-on" approach with a barrier of about 45 kJ/mol . The addition 1+H2→3 is fulfilled in two steps, the 2 + 2 addition toethenylenene carbene, then followed by 1,2-hydrogen migration. Because of the symmetry prohibition, the 2+2 addition proceeds via a 3-center transition state with a high barrier, the 4-center interaction occurs in the later stage. The reactions 1 + H2 are kinetically controlled with 2 as the major product. The requirements for the carbene addition are discussed.更多还原