Reactivity and spectroscopy of the {Ru(DMAP)5} fragment: An {Ru(NH3)5} analogue

Abstract

Reaction of trans-Ru(DMSO)4Cl2 with DMAP (DMAP = 4-dimethylaminopyridine) yields the yellow [Ru(DMAP)6]2+ cation in good yield. The crystal and molecular structure of [Ru(DMAP) 6]Cl2·6CH3CH2OH was determined by X-ray diffraction methods. The complex crystallizes in the trigonal R3 space group with a = b = 16.373(1), c = 20.311(1) Å, γ = 120°, and Z = 3 molecules per unit cell. The reaction of [Ru(DMAP) 6]2+ in aerobic water gives the red [Ru III(DMAP)5(OH)]2+ cation. This complex shows a chemical behavior similar to [RuIII(NH3) 5Cl]2+ and allows the preparation of a family of [Ru(DMAP)5L]n+ complexes. Their electronic properties indicate that the {RuIII(DMAP)5} fragment is a weaker π-donor than {RuIII(NH3)5}. Our density functional theory (DFT) calculations show that in {RuII(DMAP) 5} the DMAP ligands can compete for the π electron density of the ruthenium making the fragment a weaker π-donor.