钼(钨)-钼-硫簇合物的^(95)Mo NMR研究

Study on the ^(95)Mo NMR of Some Mo(W)-Mo-S Cluster Compounds

对含有[MS4]2-（M＝Mo，W）单元的一系列钼（钨）-钼-硫簇合物进行了95MoNMR研究，定性分析了95Mo化学位移随金属原子配位数、配位金属种类和配位金属配体改变而变化的规律。结果表明，随着[MoS4]2-配位金属原子数的增加，[MoS4]2-上Mo的化学位移逐渐向高场移动，这可归因于低氧化态MO0上的电子通过硫桥离域到高氧化态的Mo上。为了解析Mo0上化学位移的实验结果，采用MM＋力场对[（OC）4MOS2MoS2]2-和[｛（OC）4Mo｝MoS4]2-的晶体结构进行几何优化，使之更接近于溶液中的结构，然后利用Fenske－Hall方法计算Mo原子上的净电荷分布，计算结果较好地好择了Mo和Mo0化学位移的变化趋势。

The 95Mo NMR spectra of some Mo(W) - Mo- S cluster compounds containing [MS4]2-(M=Mo, W) moiety are investigated here. The trends of 95Mo chemical shifts changing withthe numbers of coordinated metal atoms, the kinds of coordinated metals and the ligands bindingwith coordinated metals are analyzed. It is found that the chemical shift of Mov1 on [MoS4]2-moves to upfield as the number of coordinated metal atoms increases. This may be due to thecharge transfer from Mo to Mov1 through S- bridges. In order to prove the experimental data ofMo, the net charges of Mo atoms in [(OC)4MoS2MoS2]2- and [ { (OC)4Mo },MoS4]2- clustersare calculated using Fenske-Hall method based on the optimized crystal structure data. The cal-culated results can reasonably explain the trends of the chemical shifts of Mo and Mo.