Ru(II) complexes with the ligand 1,2-cis(diphenylphosphino)ethylene: Chemical and electrochemical synthesis, characterization and X-ray structure

The synthesis of [RuL1L2(dppen)(2)], where L-1 = L-2 = Cl (I); L-1 = H, L-2 = Cl (II); [HRuCO(dppen)(2)] (PF6) (III), is described. The cis- and trans-[RuCl2(dppen)(2)] (dppen = 1,2-cis(diphenylphosphino)ethylene) isomers have been chemically synthesized using the [RuCl2(PPh3)(3)] precursor. Furthermore, these isomers were obtained by exhaustive controlled potential coulometry, starting from the trans-hydride [HRuCl(dppen)(2)] complex in dichloromethane. The trans-[RuCl2(dppen)(2)] species can also be obtained by electrochemical transformation from the cis isomer, with the oxidized intermediate trans-[RuCl2(dppen)(2)](+) detected by EPR measurements and cyclic voltammetry. All complexes herein described were fully characterized by spectroscopic techniques. Crystals of trans-[RuCl2(dppen)(2)] were obtained from dichloromethane/hexane and its X-ray structure determined. The crystals belong to the monoclinic space group P2(1)/c, a = 11.480(2), b = 13.061(2), c = 17.500(3) Angstrom, beta = 95.28(1)degrees, and the structure was solved by conventional heavy atom methods and refined by full-matrix least-squares procedures to R = 0.059 from 2720 reflections with I greater than or equal to 3 sigma(I).