The synthesis, magnetic, electrochemical, and spectroscopic properties of diruthenium( II , II ) tetra-µ-carboxylates and their adducts. X-Ray structures of Ru 2 (O 2 CR) 4 L 2 (R = Me, L = H 2 O or tetrahydrofuran; R = Et, L = Me 2 CO)

The interaction of the reduced ‘blue solutions’ of ruthenium chloride in methanol with alkali-metal carboxylates yields the air-sensitive paramagnetic complexes, Ru2(µ-O2CR)4(R = H, Me, CH2Cl, Et, or Ph), that form weakly end-co-ordinated bis adducts, Ru2(µ-O2CR)4L2[L = H2O, MeOH, tetrahydrofuran (thf), Me2CO, or MeCN]. Electrochemical measurements, electronic and i.r. absorption spectra, and magnetic susceptibility data are given. The structures of Ru2(O2CMe)4L2(L = H2O or thf) and Ru2(O2CEt)4(Me2CO)2 have been determined by X-ray crystallography and the well known D4h symmetry of binuclear tetracarboxylates established. The Ru2(O2CR)4 core shows a constant geometry with Ru–Ru = 2.261 ± 0.001 Å. The three axial donor ligands show slightly varying Ru ⋯ O distances of 2.335(4), 2.363(5), and 2.391(5)Å for water, acetone, and thf respectively.