Crystal structure, electrochemical and spectroscopic investigation of mer -tris-[2-(1 H -imidazol-2-yl-κ N 3 )pyrimidine-κ N 1 ]ruthenium(II) bis-(hexa-fluorido-phosphate) trihydrate

The crystal structure of the title compound, [Ru(C H N ) ](PF ) ·3H O, a novel Ru complex with the bidentate ligand 2-(1 -imidazol-2-yl)pyrimidine, comprises a complex cation in the form exclusively, with a distorted octa-hedral geometry about the ruthenium(II) cation. The Ru-N bonds involving imidazole N atoms are comparatively shorter than the Ru-N bonds from pyrimidine because of the stronger basicity of the imidazole moiety. The three-dimensional hydrogen-bonded network involves all species in the lattice with water mol-ecules inter-acting with both counter-ions and NH hydrogen atoms from the complex. The supra-molecular structure of the crystal also shows that two units of the complex bind strongly through a mutual N-H⋯N bond. The electronic absorption spectrum of the complex displays an asymmetric band at 421 nm, which might point to the presence of two metal-to-ligand charge-transfer (MLCT) bands. Electrochemical measurements show a quasi-reversible peak referring to the Ru /Ru reduction at 0.87 V Ag/AgCl.