Dinuclear Tris(1-pyrazolyl)methane Complexes of Ru(II)

By exploiting the "complexes-as-metals/complexes-as-ligands" synthetic strategy, six new dinuclear achiral complexes of Ru(II), containing the tripodal ligand tris(1-pyrazolyl) methane (tpm), a chelating ligand (L-L) such as 2,2'-bipyridine (2,2'-bpy), 1,10-phenanthroline (phen) or 2,2'-biquinoline (biq), and either pyrazine (pz) or 4,4'-bipyridine (4,4'-bpy) as bridging ligands (BL), have been prepared and fully characterized. The starting building blocks, many of which have been synthesized for the first time, have been conveniently prepared by improved literature methods. The reactivity of these building blocks in specific experimental conditions has been rationalized. All novel compounds have been characterized fully by elemental analysis and FT-IR. (1)H NMR spectra have been carefully assigned and interpreted on the basis of possible inductive and magnetic anisotropic effects exerted by the ligands. Electrochemical, UV/Vis spectroscopic, and luminescence studies have been carried out on all the dinuclear complexes and their precursor species; the collected data have been discussed and thoroughly interpreted. Ru(II)/Ru(III) mixed-valence species of two dinuclear compounds have been investigated by spectroelectrochemistry and assigned to the Robin and Day's Class II group on the basis of the experimental parameters obtained