Mechanism of the photochemical ligand substitution reactions of fac-[Re(bPY)(CO)3(PR3)]+ complexes and the properties of their triplet ligand-field excited states
Mechanism of the photochemical ligand substitution reactions of fac-[Re(bPY)(CO)3(PR3)]+ complexes and the properties of their triplet ligand-field excited states
复制标题
DOI：
10.1021/ja017032m
复制
发表时间：
2002-09-25
影响因子：
15
通讯作者：
Turner, JJ
中科院分区：
文献类型：
--
作者：
Koike, K;Okoshi, N;Turner, JJ
本文报道了一系列Fac-[Re(X(2)bpy)(CO)(3)(Pr3)](+)配合物(1)的光化学取代反应机理及其三重配位场((Lf)-L-3)激发态的性质。还研究了稀土配合物[Re(X(2)bpy)(CO)(3)(Py)](+)(3)和[Re(X(2)bpy)(CO)(3)Cl](4)光稳定性的原因。在1的乙腈溶液中，选择性地合成了顺式、反式-[Re(X(2)bpy)(CO)(2)(Pr3)(CH3CN)](+)(2)。同位素实验清楚地表明，CO配体被选择性地取代为Pr3配体。光化学反应通过3LF激发态的解离机制进行。根据发光寿命、光化学反应和发射的量子产率随温度变化的数据，得到了配合物1的(LF)-L-3激发态的热力学数据和三重态金属-配体电荷转移((MLCT)-M-3)态的校正非辐射衰变速率常数。1与[Re(X(2)bpy)(CO)(3)(Py)](+)(3)和[Re(X(2)bpy)(CO)(3)Cl](4)的比较表明，某些3和4型配合物的(Lf)-L-3态即使在室温下也可能从(MLCT)-M-3态进入，但这些配合物对365 nm的辐射是稳定的。与1相比，3和4的光稳定性可以通过Pr3、Py和Cl-配体反式效应的差异来解释。
We report herein the mechanism of the photochemical ligand substitution reactions of a series of fac-[Re(X(2)bpy)(CO)(3)(PR3)](+) complexes (1) and the properties of their triplet ligand-field ((LF)-L-3) excited states The reason for the photostability of the rhenium complexes [Re(X(2)bpy)(CO)(3)(py)](+) (3) and [Re(X(2)bpy)(CO)(3)Cl] (4) was also investigated. Irradiation of an acetonitrile solution of 1 selectively gave the biscarbonyl complexes cis, trans-[Re(X(2)bpy)(CO)(2)(PR3)(CH3CN)](+) (2). Isotope experiments clearly showed that the CO ligand trans to the PR3 ligand was selectively substituted. The photochemical reactions proceeded via a dissociative mechanism from the 3LF excited state. The thermodynamical data for the (LF)-L-3 excited states of complexes 1 and the corrective nonradiative decay rate constants for the triplet metal-to-ligand charge-transfer ((MLCT)-M-3) states were obtained from temperature-dependence data for the emission lifetimes and for the quantum yields of the photochemical reactions and the emission. Comparison of 1 with [Re(X(2)bpy)(CO)(3)(py)](+) (3) and [Re(X(2)bpy)(CO)(3)Cl] (4) indicated that the (LF)-L-3 states of some 3- and 4-type complexes are probably accessible from the (MLCT)-M-3 state even at ambient temperature, but these complexes were stable to irradiation at 365 nm. The photostability of 3 and 4, in contrast to 1, can be explained by differences in the trans effects of the PR3, py, and Cl- ligands.