Co-ordination chemistry of higher oxidation states. Part 41. Synthesis, spectroscopic and electrochemical studies of cationic ruthenium(III) Group 15 and 16 donor ligand complexes. Structure of trans-[Ru{C6F4(AsMe2)2-o}2Br2]BF4
Abstract
The complexes trans-[Ru(L–L)2X2]BF4[X = Cl or Br; L–L = bidentate ligand including C6H4(PMe2)2-o, C6H4(AsMe2)2-o, C6F4(AsMe2)2-o, Me2PCH2CH2PMe2, Ph2PCH2CH2PPh2, Ph2AsCHCHAsPh2, C6H4(PPh2)2-o, C6F4(PPh2)2-o, MeSCH2CH2SMe, PhSCH2CH2SPh and PhSeCH2CH2SePh] have been prepared by nitric acid oxidation of the corresponding [Ru(L–L)2X2] in aqueous HBF4 and in other ways. The complexes have been characterised by analysis, IR and UV/VIS spectroscopies, and magnetic measurements, and the RuII–RuIII redox potentials established by cyclic voltammetry. The crystal structure of trans-[Ru{C6F4(AsMe2)2-o}2Br2]BF4 has been determined; monoclinic, space group C2/c, a= 22.080(5), b= 18.064(2), c= 8.576(3)Å, β= 96.27(3)°, R= 0.040 for 2266 reflections [F > 3σ(F)]; Ru–Br 2.455(1), Ru–As 2.457(1), 2.460(1)Å. Electrochemical studies have provided evidence for the formation of ruthenium(IV) analogues in solution at low temperatures for certain ligands, but these are too unstable to isolate by chemical means. Comparisons with the analogous iron and osmium systems are made.