NEW PIANO-STOOL RUTHENIUM(II) COMPLEXES OF BENZENE AND BIDENTATE TRIDENTATE NITROGEN-DONOR LIGANDS - SYNTHESIS AND CHARACTERIZATION

New piano-stool ruthenium(II) complexes, [Ru(eta6-C6H6)L1]2+, [Ru(eta6 -C6H6)(L2)Cl]+, [Ru(eta6-C6H6) (L3)Cl]+, [Ru(eta-C6H6)(L4)Cl]+ and [Ru (eta6-C6H6)(L5)Cl]+ have been isolated as their hexafluorophosphate sa lts by bridge-cleavage reactions of [{Ru(eta6-C6H6)Cl2}2] in methanol with the potentially tri- and bi-dentate nitrogen-containing ligands [ 2-(2-pyridyl)ethyl] (2-pyridylmethyl)methylamine (L1), 2,6-bis(pyrazol -1-ylmethyl)pyridine (L2) and its tetramethyl-substituted derivative ( L3), 2-(pyrazol-1-ylmethyl)pyridine (L4) and its dimethyl derivative ( L5). The structures of these compounds in MeCN solution have been eluc idated by H-1 NMR spectroscopy. The complex [Ru(eta6-C6H6)L1][PF6]2 ha s been characterized by single-crystal X-ray crystallography: triclini c, space group P1BAR (no. 2), a = 7.790(3), b = 10.039(3), c = 16.679( 5) angstrom, alpha = 88.31(2), beta = 83.15(3), gamma = 77.19(3)degree s and Z = 2. The structure has been refined to an R factor of 0.063 ba sed on 5330 observed reflections. Average Ru-C and Ru-N (two types) bo nd lengths are 2.202(6) and 2.114(5) and 2.170(5) angstrom respectivel y.