Details

Autor(en) / Beteiligte

• Mukuta, Tatsuhiko
• Simpson, Peter V
• Vaughan, Jamila G
• Skelton, Brian W
• Stagni, Stefano
• Massi, Massimiliano
• Koike, Kazuhide
• Ishitani, Osamu
• Onda, Ken

Titel

Photochemical Processes in a Rhenium(I) Tricarbonyl N‑Heterocyclic Carbene Complex Studied by Time-Resolved Measurements

Ist Teil von

• Inorganic chemistry, 2017-03, Vol.56 (6), p.3404-3413

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2017

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• We carried out time-resolved infrared (TR-IR) and emission lifetime measurements on a Re­(I) carbonyl complex having an N-heterocyclic carbene ligand, namely, fac-[Re­(CO)3(PyImPh)­Br], under photochemically reactive (in solution in acetonitrile) and nonreactive (in solution in dichloromethane) conditions to investigate the mechanism of photochemical ligand substitution reactions. The TR-IR measurements revealed that no reaction occurs on a picosecond time scale and the cationic product, namely, fac-[Re­(CO)3(PyImPh)­(MeCN)]+, is produced on a nanosecond time scale only in solution in acetonitrile, which indicates that the reaction proceeds thermally from the excited state. Because no other products were observed by TR-IR, we concluded that this cationic product is an intermediate species for further reactions. The measurements of the temperature-dependent emission lifetime and analysis using transition-state theory revealed that the photochemical substitution reaction proceeds from a metal-to-ligand charge transfer excited state, the structure of which allows the potential coordination of a solvent molecule. Thus, the coordinating capacity of the solvent determines whether the reaction proceeds or not. This mechanism is different from those of photochemical reactions of other types of Re­(I) carbonyl complexes owing to the unique characteristics of the carbene ligand.