Synthesis and structure of trans-dimethylammonium bis(oxalato)diaquaruthenate(III) tetrahydrate

Trans-Dimethylammonium bis(oxalato)diaquaruthenate(III) tetrahydrate, trans-[(CH3)2NH2][Ru(C2O4)2(H2O)2]·4H2O, was synthesized by diffusion of dimethylamine (from dimethylformamide) into a refluxed aqueous solution of diruthenium(II,III) tetraacetate and oxalic acid. The structure of the complex was determined by X-ray diffraction. The RuO (oxalate) and RuO (water) distances are 2.041(3) and 1.994(3) Å, respectively and the oxalate bite angle is 80.6(2)°. The complex displays an intricate pattern of inter- and intra-chain hydrogen bonding involving the axial water molecules, the water molecules of hydration, the dimethylammonium cation, and the carbonyl and carboxyl oxygens of the oxalate groups. Additional characterization using infrared and UV–Vis spectroscopies, magnetic susceptibility (isothermal and variable temperature), and cyclic voltammetry is also reported.