The 4-(dipyridylamino)benzoylpyridine ligand as a supramolecular synthon. Solid state organization of a bis(bipyridyl)ruthenium(II) complex

The bis(2,2′-bipyridyl)ruthenium(II) derivative [Ru(bpy)2(p-py2N(C6H4)C(O)py)][PF6]2 was prepared by reaction between ‘[Ru(bpy)2(EtOH)2][PF6]2’ and an excess of p-py2N(C6H4)C(O)(py). X-ray analysis shows that the ruthenium is coordinated via the N,O ligand set rather than the via the N,N′-dipyridylamino fragment. The cations are arranged in dimeric units as a result of (C)H⋯N weak hydrogen bonding interactions. The dimeric units are further organized into a supramolecular chain structure of cations by π–π stacking interactions involving bipyridyl ligands and by weak CH⋯O interactions. The complicated 1H and 13C NMR spectra were completely assigned by using two-dimensional methods. The optical spectra in CH3CN show two high-energy ligand-based absorption maxima that show a small bathochromic shift when compared to the spectral data of the free arylpyridylmethanone ligand and two long-wavelength absorption maxima centered near 440 and 574 nm that are assigned to Ru(dπ)–π*(py) and Ru(dπ)–π*[ArC(O)(py)] MLCT transitions, respectively. The cyclic voltammogram shows an irreversible oxidation wave for the Ru(II)/(III) couple at +1.31 V versus SCE.