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

Kazuhide Koike, Nobuaki Okoshi, Hisao Hori, Koji Takeuchi, Osamu Ishitani, Hideaki Tsubaki, Ian P. Clark, Michael W. George, Frank P.A. Johnson, James J. Turner

Research output: Journal PublicationArticlepeer-review

138 Citations (Scopus)

Abstract

We report herein the mechanism of the photochemical ligand substitution reactions of a series of fac-[Re(X2bpy)(CO)3(PR3)]+ complexes (1) and the properties of their triplet ligand-field (3LF) excited states. The reason for the photostability of the rhenium complexes [Re(X2bpy)(CO)3(py)]+ (3) and [Re(X2bpy)(CO)3Cl] (4) was also investigated. Irradiation of an acetonitrile solution of 1 selectively gave the biscarbonyl complexes cis,trans-[Re(X2bpy)(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 3LF excited states of complexes 1 and the corrective nonradiative decay rate constants for the triplet metal-to-ligand charge-transfer (3MLCT) 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(X2bpy)(CO)3(py)]+ (3) and [Re(X2bpy)(CO)3Cl] (4) indicated that the 3LF states of some 3- and 4-type complexes are probably accessible from the 3MLCT 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.

Original languageEnglish
Pages (from-to)11448-11455
Number of pages8
JournalJournal of the American Chemical Society
Volume124
Issue number38
DOIs
Publication statusPublished - 25 Sep 2002
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry (all)
  • Biochemistry
  • Colloid and Surface Chemistry

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