The synthesis, magnetic, electrochemical, and spectroscopic properties of diruthenium(II,II) tetra-µ-carboxylates and their adducts. X-Ray structures of Ru2(O2CR)4L2(R = Me, L = H2O or tetrahydrofuran; R = Et, L = Me2CO)

Abstract

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 D_4h 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.