Synthesis, characterisation and dynamic behavior of photoactive bipyridyl ruthenium(II)-nicotinamide complexes

The dynamic behavior of three bisbipyridylruthenium(II)-nicotinamide complexes was demonstrated by temperature-dependent 1H NMR spectroscopy which revealed hindered rotation of nicotinamide in the X = chlorido and X = iodido complexes at ambient temperature. In contrast free rotation of nicotinamide on the NMR timescale was observed for the bisnicotinamide (X = nicotamide) complex at 298 K. DFT calculations suggested that hindered rotation is associated with intramolecular H-bonding which is strongest for the chlorido complex.147