Synthetic, spectral and structural study of mono bis(pyridine)dichloro bis(dimethyl sulfoxide-S) ruthenium(II) complex, [RuCl2(py)2(dmso-S)2] and its reactivity with nitrogen donor bases in polar and non-polar solvent

Reaction of the cis-[RuCl2(dmso)4] with pyridine (py) at room temperature in MeOH/H2O afforded a neutral mononuclear complex cis,cis,cis-[RuCl2(py)2(dmso-S)2] 1. The complex 1 reacted with nitrogen donor bases such as pyridine (py), pyrazine (pyz), 4,4′-bipyridine (bp) and 1,4-bis(4-pyridyl)ethane (bpeta) in different solvents to give substitution products. The nature of the substitution product was governed by the polarity of the solvents employed in the reaction. Resulting complexes have been characterized by elemental analyses, IR, NMR (1H and 1H–1H COSY), ESI-MS, FAB-MS and electronic spectral studies. Molecular structures of the complexes 1 and 5 have been determined crystallographically. Complex 1 exhibits the strong intra- and inter-molecular CH⋯X (X = Cl, π) and face-to-face π–π stacking interactions but only intra- and inter-molecular CH⋯Cl and π–π stacking interactions are present in 5 which play important roles to stabilize crystal packing. Furthermore, the CH⋯O interactions in 1 and CH⋯Cl interactions in 5 lead to a single and double-helical motif.