Syntheses, crystal structures, susceptibility and EPR studies of oxo-bridged dinuclear ruthenium (III) complexes with linear Ru–O–Ru bonds: and [(Py)3(C2O4)RuIIIORuIII(C2O4)(Py)3] and [(4-MePy)3(C2O4)RuIIIORuIII(C2O4)(4-MePy)3]·2-Mebmz ·3H2O (Py = pyridin

Two oxo-bridged dinuclear ruthenium(III) complexes, [(Py)3(C2O4)RuIIIORuIII(C2O4)(Py)3] (1) and [(4-MePy)3(C2O4)RuIIIORuIII(C2O4)(4-MePy)3]·2-Mebmz ·3H2O (2) (Py = pyridine; 4-MePy = 4-Methylpyridine; 2-Mebmz = 2-methylbenzimidazole) were prepared by reacting RuCl3 with K2C2O4 and pyridine or 4-Methylpyridine and characterized by spectral data and X-ray crystallography. In both (1) and (2), the Ru–O–Ru bonds are linear, with the two C2O42− ions trans to each other at the terminal positions. The magnetic susceptibility of (1) was analyzed using a general isotropic exchange Hamiltonian H=−2JS1·S2 (S1=S2=1/2), yielding an antiferro-magnetic spin coupling constant J=−53 cm−1.