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. 2008 Nov 27;112(47):12071-80. doi: 10.1021/jp806110h.
Reactions of laser-ablated group 6 metal atoms with ethylene have been investigated. The insertion and dihydrido products (MH-CHCH(2) and MH(2)-C(2)H(2)) are identified from reactions of W and Mo with ethylene isotopomers, whereas products in the Cr spectra are assigned to the insertion and metallacyclopropane (M-C(2)H(4)) complexes. Our experiments with CH(2)CD(2) show that the dihydrido complex is formed by beta-hydrogen transfer in the insertion complex because the MHD-CHCD isotopic product is favored. The present matrix infrared spectra and DFT computational results support the general trend that the higher oxidation-state complexes become more stable on going down the group 6 column. Unlike the cases of group 4 and 5 metals, binary metal hydride (MH(x)) absorptions are not observed in the infrared spectra, suggesting that the H(2)-elimination reactions of ethylene by group 6 metals are relatively slow, consistent with previous gas-phase reaction dynamics studies.
研究了激光烧蚀的第6族金属原子与乙烯的反应。从钨和钼与乙烯同位素异构体的反应中鉴定出插入产物和二氢化物产物（MH-CHCH(2)和MH(2)-C(2)H(2)），而铬光谱中的产物则归属于插入产物和金属环丙烷（M-C(2)H(4)）配合物。我们用CH(2)CD(2)进行的实验表明，二氢化物配合物是由插入配合物中的β-氢转移形成的，因为MHD-CHCD同位素产物占优势。目前的基质红外光谱和密度泛函理论计算结果支持了这样一个总体趋势：随着第6族元素的原子序数增加，高氧化态配合物变得更加稳定。与第4族和第5族金属的情况不同，在红外光谱中未观察到二元金属氢化物（MH(x)）的吸收，这表明第6族金属使乙烯发生H(2)消除反应的速率相对较慢，这与之前的气相反应动力学研究结果一致。
