Electronic peculiarities of the excited states of [RuN5C]+vs. [RuN6]2+ polypyridine complexes: insight from theory

Abstract

The ground state, oxidized ground state, ³MLCT and ³MC excited states have been studied by DFT and TDDFT for two Ru(II) complexes bearing an N₆ or N₅C coordination sphere. The effect of replacing one Ru–N dative bond by one Ru–C covalent bond have been studied and quantified on their ground state by the means of geometry optimization, NBO analysis and calculation of their IR vibrations. IR fingerprints of the Ru–C bond have been found at 945 and 1113 cm⁻¹. In addition, this study confirmed and quantified the effects of N→C⁻ substitution on the spectroscopic properties of the [RuN₅C]⁺ complex: a broader and bathochromically-shifted absorption spectrum, a smaller ground–³MLCT energy gap and a highly energetic ³MC state are the major characteristics of the carbon-containing monocationic complex.