Electron localisation in electrochemically reduced mono- and bi-nuclear rhenium(i) complexes with bridged polypyridyl ligands
作者:Simon E. Page、Amar Flood、Keith C. Gordon
DOI:10.1039/b110730p
日期:——
A number of mono- and bi-nuclear rhenium(I) complexes have been prepared and their physical properties, including the infrared spectra of the reduced complexes, have been studied. These compounds have the general formula [Re(CO)3Cl(L)] and [Cl(CO)3Re(μ-L)Re(CO)3Cl], where L can be 2,3-(2′,2″)-diquinolylquinoxaline, 6,7-dimethyl-2,3-(2′,2″)-diquinolylquinoxaline, 2,3-(2′,2″)-diquinolylbenzoquinoxaline, 6,7-dichloro-2,3-(2′,2″)-diquinolylquinoxaline, 2,3-(2′,2″)-diquinoxalylquinoxaline, 6,7-dimethyl-2,3-(2′,2″)-diquinoxalylquinoxaline, 2,3-(2′,2″)-diquinoxalylbenzoquinoxaline and 6,7-dichloro-2,3-(2′,2″)-diquinoxalylquinoxaline. The electrochemical studies show that the first reduction potential of the free ligands correlates with the reductions of the corresponding mono- and bi-nuclear complexes. The properties of the complexes
have been modelled using semi-empirical methods. These show linear correlations between: (a) the energy of the MLCT transitions versus the difference in energy between the LUMO and the HOMO and (b) the change in carbonyl force constant with reduction vs. the wavefunction amplitude of the π* LUMO at the site of coordination. The experimental data and calculations point to significant alterations in the π* LUMO with substitution at the ligand and with the chelation of a second Re(I) center.
我们制备了一些单核和双核铼(I)络合物,并研究了它们的物理性质,包括还原络合物的红外光谱。这些化合物的通式为[Re(CO)3Cl(L)]和[Cl(CO)3Re(μ-L)Re(CO)3Cl],其中 L 可以是 2,3-(2′,2″)-二喹啉基喹喔啉、6,7-二甲基-2,3-(2′,2″)-二喹啉基喹喔啉、2,3-(2′,2″)-二喹啉基苯喹喔啉、6、2,3-(2′,2″)-二喹喔啉基喹喔啉、2,3-(2′,2″)-二喹喔啉基喹喔啉、6,7-二甲基-2,3-(2′、2,3-(2′,2″)-二喹喔啉基苯喹喔啉和 6,7-二氯-2,3-(2′,2″)-二喹喔啉基喹喔啉。电化学研究表明,游离配体的第一还原电位与相应的单核和双核络合物的还原电位相关。这些络合物的性质是用半经验方法模拟出来的。这些结果表明:(a) MLCT 转变的能量与 LUMO 和 HOMO 之间的能量差;(b) 羰基力常数随还原的变化与配位处 π* LUMO 的波函数振幅之间存在线性相关关系。实验数据和计算结果表明,随着配体的取代和第二个 Re(I) 中心的螯合,π* LUMO 发生了显著变化。