Photochemical Processes in a Rhenium(I) Tricarbonyl N-Heterocyclic Carbene Complex Studied by Time-Resolved Measurements
MetadataShow full item record
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.
Funding and Sponsorship
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see 10.1021/acs.inorgchem.6b02936, see http://pubs.acs.org/page/policy/articlesonrequest/index.html.
Showing items related by title, author, creator and subject.
Simpson, Peter; Falasca, Marco; Massi, Massimiliano (2018)Re(i) complexes bound to p-conjugated bidentate N-heterocyclic carbene ligands with formulation Re(CO)3(N^NHC)L (where N^NHC represents an imidazole or benzimidazole carbene ligand conjugated to a N-based heterocycle such ...
Photophysical and Photochemical Studies of Tricarbonyl Rhenium(I) N-Heterocyclic Carbene Complexes Containing Azide and Triazolate LigandsSimpson, Peter V.; Skelton, B.; Raiteri, Paolo; Massi, Massimiliano (2016)Rhenium(I) N-heterocyclic carbene (NHC) complexes of the type fac-[Re(CO)3(NHC)L] with either azide or triazolate ancillary ligands L and pyridyl or pyrimidyl substituted imidazolyl units have been prepared and structurally ...
Vaughan, J.; Reid, Brodie; Wright, Phillip; Ramchandani, S.; Skelton, B.; Raiteri, Paolo; Muzzioli, S.; Brown, David; Stagni, S.; Massi, Massimiliano (2014)A family of tricarbonyl Re(I) complexes of the formulation fac-[Re(CO)3(NHC)L] has been synthesized and characterized, both spectroscopically and structurally. The NHC ligand represents a bidentate N-heterocyclic carbene ...