Mono‐ and Dinuclear Complexes of Tricarbonylrhenium(I) with 4‐Methyl‐2,2′‐bipyridine‐4′‐carbonitrile

Abstract

AbstractNovel mono‐ and dinuclear tricarbonylrhenium(I) complexes of formula [Re(Mebpy‐CN)(CO)3Cl] (1), [Re(Mebpy‐CN)(CO)3(CH3CN)](PF6) (2), and [(CH3CN)(CO)3Re(Mebpy‐CN)Ru(NH3)5](PF6)3 (3), in which Mebpy‐CN = 4‐methyl‐2,2′‐bipyridine‐4′‐carbonitrile, were prepared and characterized by spectroscopic, photophysical, and computational techniques. The complete structure of complex 2 was determined by X‐ray diffraction. The increased conjugation in the bipyridyl ring owing to the nitrile substituent increases the emission quantum yields of the 3MLCT (metal‐to‐ligand charge‐transfer) lowest‐lying excited states of 1 and 2 with respect to the corresponding bpy complexes (bpy = 2,2′‐bipyridine). The mixed‐valent species of formula [(CH3CN)(CO)3Re(Mebpy‐CN)Ru(NH3)5]4+ (4) was prepared in situ and as a mixed salt; the charge recombination from its metal‐to‐metal charge‐transfer (MMCT) excited state is predicted to lie in the Marcus inverted region. The electronic structures and optical properties of all the reported complexes calculated by DFT and TD‐DFT methods agree reasonably well with experimental results.