Study of 4d and 5d transition metal cluster complexes in aiming at systematic understanding of metal-to-metal interaction.

合成了一些新的重过渡元素金属簇合物，如钼、钨、Ru、Os、Re和铂，并用X射线结构分析确定了它们的结构。一系列的双氧桥联配合物包括单键到三键的金属-金属键合络合物，包括1.5和2.5的键级，提供了键级与金属-金属距离之间的良好关联。它们表现出多步单电子氧化还原行为，光谱电化学结果提供了不同氧化态的电子态信息。不同桥联基团的(Mu-O)、Mu-O(Mu-O)和(Mu-O)(Mu-RCOO)的(III，IV)混合价态的比例常数非常高(约10^&lt；20&gt；)。结构相似的Ru和Re络合物的值要小得多。合成了几种新的(Mu-O)(Mu-RCOO)和(Mu-O)(Mu-RCOO)_2桥基混合桥联配合物。它们还表现出多步单电子转移行为。特别令人感兴趣的是在乙腈中通过添加不同酸度的质子供体来研究质子耦合的氧化还原反应。通过控制加酸的pKa，我们找到了表现质子耦合一步两电子转移行为的条件。没有观察到二(Mu-O)和单(Mu-O)络合物的质子耦合氧化还原行为，这表明这些络合物的质子化过程有更高的重组势垒。

A number of new metal cluster complexes of heavy transition elements such as molybdenum, tungsten, ruthenium, osmium, rhenium, and platinum, have been prepared, and their structures have been determined by X-ray structural analysis. A series of doubly oxide bridged complexes include single to triple metal-metal bonded complexes including bond-order of 1.5 and 2.5 provide good correalation between bond-order and metal-metal distances. They show multi-step one-electron redox behavior, spectroelectrochemical results of which provide information on electronic states of different oxidation states. Remarkably high comproportionation constants (ca. 10^<20>) for the (III,IV) mixed valence states are noted for osmium complexes of various bridging moieties such as di (mu-O), mono (mu-O) and (mu-O) (mu-RCOO). Ruthenium and rhenium complexes with similar structures show much smaller values. Several new mixed-bridged complexes of (mu-O) (mu-RCOO) and (mu-O)(mu-RCOO)_2 bridging group have been prepared for ruthenium and osmium. They also show multi-step one-electron transfer behavior. Of particular interest is the proton-coupled redox reactions in acetonitrile as studied by adding various proton donors with different acidity. By controlling the pKa of added acid, we found the condition to show proton-coupled one-step two-electron transfer behavior. Proton-coupled redox behavior has not been observed for the di (mu-O), and mono (mu-O) complexes, indicating much higher reorganizing barrier for the protonation processes of these complexes.