Cho Han-Gook, Andrews Lester
Department of Chemistry, University of Incheon, 177 Dohwa-dong, Nam-ku, Incheon, 402-749, South Korea.
J Phys Chem A. 2007 Jun 21;111(24):5201-10. doi: 10.1021/jp0702806. Epub 2007 May 25.
Reactions of ethylene with laser-ablated group 5 metal atoms in excess argon have been carried out during codeposition at 8 K, and the matrix infrared spectra of intermediate products have been investigated. Oxidative C-H insertion of the transition metal into a C-H bond occurs and beta-hydrogen transfer follows to form the dihydrido complexes (MH2-C2H2). In the Ta spectra, the dihydrido complex is the primary product, whereas the Nb and V spectra reveal absorptions from both the insertion (MH-C2H3) and dihydrido complexes. The insertion and dihydrido complexes identified here are in fact the reaction intermediates in the hydrogen elimination of ethylene proposed in previous reaction dynamics studies. Calculations also show that the higher oxidation-state complex becomes more stable relative to the insertion product going down the group 5 family.
在8K共沉积过程中，进行了乙烯与在过量氩气中激光烧蚀的第5族金属原子的反应，并研究了中间产物的基质红外光谱。过渡金属发生氧化C-H插入到C-H键中，随后发生β-氢转移，形成二氢配合物（MH2-C2H2）。在钽的光谱中，二氢配合物是主要产物，而铌和钒的光谱显示了插入产物（MH-C2H3）和二氢配合物的吸收峰。这里鉴定出的插入产物和二氢配合物实际上是先前反应动力学研究中提出的乙烯氢消除反应的中间体。计算还表明，相对于插入产物，第5族元素中氧化态较高的配合物随着族序数的降低变得更稳定。
