RuII Electron Transfer Systems Containing S-Donor Ligands

The synthesis and properties of 3 new ligand-bridged bimetallic complexes, 12+, 22+, and 32+, containing [RuCl([9]aneS3)]+ metal centers are reported. Each complex was bridged by a different ditopic ligand. 12+ is bridged by 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz), while 22+ and 32+ are bridged by 2,3-bis(2-pyridyl)pyrazine (dpp) and 2,2‘-bipyrimidine (bpym), respectively. The Ru[II] isovalent states of these complexes have been investigated using a variety of techniques. In the case of 32+, X-ray crystallography studies show preferential crystallization of an anti form with respect to coordinated chloride ligands (crystal data for [3][Cl2]·4H2O:  C20H38Cl4N4O4Ru2S6, monoclinic, space group P21/a, a = 10.929(14), b = 13.514(17), c = 11.299(16) A, β = 90.52(1), V = 1669 A3, Z = 2). UV/vis spectroscopy shows that spectra of these complexes are dominated by intraligand (π→π*) and metal-to-ligand Ru(d)→L(π*) charge transfer transitions. Electrochemical studies reveal that metal−metal interactions are suff...