Synthesis, characterisation and theoretical studies on some piano-stool ruthenium and rhodium complexes containing substituted phenyl imidazole ligands

Reactions of the chloro-bridged arene ruthenium complexes [{(η6-arene)RuCl(μ-Cl}2] (η6-arene = benzene, p-cymene) and structurally analogous rhodium complex [{(η5-C5Me5)RhCl(μ-Cl}2] with imidazole based ligands viz., 1-(4-nitro-phenyl)-imidazole (NOPI), 1-(4-formylphenyl)-imidazole (FPI) and 1-(4-hydroxyphenyl)-imidazole (HPI) have been investigated. The resulting complexes have been characterised by elemental analyses, IR, 1H and 13C NMR, electronic absorption and emission spectral studies. Crystal structure of the representative complex [(η5-C5Me5)RhCl2(NOPI)] has been determined crystallographically. Geometrical optimisation on the complexes have been performed using exchange correlation functional B3LYP. Optimised bond lengths and angles of the complexes have been found to be in good agreement with our earlier reports and single crystal X-ray data of the complex [(η5-C5Me5)RhCl2(NOPI)].