Photochemical and photophysical properties of [Mn(imidazole)(CO) 3(phen)](SO 3CF 3) complexes

Abstract

The photoreactions resulting from metal-to-ligand charge transfer (MLCT) excitation of the manganese(I) tricarbonyl complexes fac-[Mn(CO) 3(phen)(Im)](SO 3CF 3) and fac-[Mn(CO) 3(phen)(Im-CH 3)](SO 3CF 3) in several solvents at various wavelengths are reported. In each case, the reaction product is the corresponding mer-[Mn(CO) 3(phen)(Im-L)] + isomer. The high quantum yields, ∼0.66 mol einstein −1, reflect accurately primary photoprocesses from ligand-field states which are measured in a time scale during which thermal or secondary photoprocesses are not important. Further, in competition to ligand-field photoisomerization, these complexes are luminescent at room temperature. The emitting state can be tuned from a MLCT emission to intra-ligand (IL) fluorescence by varying the solvent polarity and excitation wavelength. Alterations in the character of the excited state result in large changes in the emission spectra suggesting the use of these complexes as probes.