Structural, spectroscopic and redox studies of trans-[RuX2L4]0/+ (L = PR3, AsR3 or SbR3; X = Cl, Br or I). Crystal structures of trans-[RuX2(EMe2Ph)4] (X = Br, E = Sb; X = I, E = As), [Ru2Br5(SbMe2Ph)4] and [Ru2I3(PMe2Ph)6][CF3SO3]

Abstract

The complexes trans-[RuX₂L₄] (X = Cl, Br or I; L = PMe₃, AsMe₂Ph or SbMe₂Ph) have been prepared from RuCl₃·nH₂O, LiX and L, from [Ru(dmf)₆][CF₃SO₃]₃ (dmf = N,N-dimethylformamide), LiX and L, and in other ways. The complexes cis-[RuX₂(PMe₂Ph)₄] (X = Cl or Br) have been made from [RuX₂(PPh₃)₃] and PMe₂Ph in hexane and cis-[RuX₂(PMe₃)₄] from solutions of the trans isomers on standing in CH₂Cl₂. Oxidation of trans-[RuX₂L₄] to trans-[RuX₂L₄]BF₄ has been achieved either with AgBF₄ in CH₂Cl₂ or concentrated HNO₃ in aqueous HBF₄. The complexes have been characterised by analysis, UV/VIS, IR, ¹H and ³¹P-{¹H} NMR spectroscopy as appropriate, and the Ru^II–Ru^III oxidations probed by cyclic voltammetry. The behaviour of this series of complexes is compared with that of the osmium [OsX₂L₄]^0/+/2+ analogues. The crystal structures of trans-[RuX₂L₄] (X = I, L = AsMe₂Ph; X = Br, L = SbMe₂Ph), [Ru₂Br₅(SbMe₂Ph)₄] and [Ru₂I₃(PMe₂Ph)₆][CF₃SO₃] have been determined.