Pyrazolylborate-zinc-hydrosulfide complexes and their reactions.
Pyrazolylborate-zinc-hydrosulfide complexes and their reactions.
复制标题
吡唑基硼酸锌硫氢化物配合物及其反应。
作者：
M. Rombach;H. Vahrenkamp
以取代吡唑基硼酸类配体(TP*)为原料，通过与H(2)S反应，合成了4种新的硫化物配合物TP*Zn-SH，其中3种对其结构进行了表征。与TP*锌-OH络合物不同，它们不与酯、磷酸盐或CO(2)反应，例如硫解裂解反应。它们也不能去质子化，因为不同的碱会导致硫化锌的沉淀和阴离子TP*的释放。酸性有机X-OH化合物(羧酸、三硝基苯酚、六氟乙酰丙酮)以TP*Zn-OX取代SH基团。硫醇经过熵驱动的SH取代反应生成TP*锌-SR络合物。与TP*锌-SR络合物一样，TP*锌-SH络合物与甲基碘发生烷基化反应，生成TP*Zn-I和CH(3)SH。对TP(Ph，Me)Zn-SH甲基化反应的动力学研究表明，它是一个干净的二级反应，从而表明SH基团是以锌键合状态烷基化的。
Four new hydrosulfide complexes Tp*Zn-SH of substituted pyrazolylborate ligands (Tp*) were prepared by reactions of Tp*Zn-OH with H(2)S, and three of them were structurally characterized. Unlike the Tp*Zn-OH complexes they do not react with esters, phosphates, or CO(2), e.g. for thiolytic cleavage reactions. They also cannot be deprotonated, as various bases induce precipitation of ZnS and release of anionic Tp*. Acidic organic X-OH compounds (carboxylic acids, trinitrophenol, hexafluoroacetylacetone) replace the SH groups with formation of Tp*Zn-OX. Thiols undergo an entropy-driven SH substitution to yield the Tp*Zn-SR complexes. Like the Tp*Zn-SR complexes the Tp*Zn-SH complexes are quite reactive toward alkylation with methyl iodide, yielding Tp*Zn-I and CH(3)SH. The kinetic investigation of the methylation of Tp(Ph,Me)Zn-SH has shown it to be a clean second-order reaction, thereby indicating that the SH group is alkylated in the zinc-bound state.