Complexes of the platinum metals. Part 25. Reactions of ruthenium and osmium nitrosyls [MH(NO)(PPh3)3] and [M(NO)2(PPh3)2] with perfluorocarboxylic acids: X-ray crystal structure determination of nitrosyl(trifluoroacetato)(trifluoroacetohydroximato-OO′)bis(triphenylphosphine)osmium(II)–dichloromethane (1/1)

Abstract

Ruthenium and osmium hydridonitrosyl complexes, [MH(NO)(PPh₃)₃], react with perfluorocarboxylic acids RCO₂H (R = CF₃ or C₂F₅) to afford the products [Ru(O₂CR)₃(NO)(PPh₃)₂] and [OsH(O₂CR)₂(NO)(PPh₃)₂] respectively. The reaction intermediates [RuH(O₂CR)₂(NO)(PPh₃)₂] and [OsH₂(NO)(PPh₃)₃]⁺ have been detected in solution by ¹H and ³¹P-{¹H} n.m.r.; the latter species has been isolated and characterised as the tetraphenylborate salt. The ruthenium dinitrosyl complex [Ru(NO)₂(PPh₃)₂] reacts with the acids RCO₂H in boiling toluene or 2-methoxyethanol to afford the products [Ru(O₂CR)₃(NO)(PPh₃)₂]. The corresponding osmium complex [Os(NO)₂(PPh₃)₂] reacts with the same acids in boiling 2-methoxyethanol and boiling toluene to yield the hydrides [OsH(O₂CR)₂(NO)(PPh₃)₂] and the novel hydroximate derivatives [[graphic omitted]R}(O₂CR)(NO)(PPh₃)₂] respectively. Possible mechanisms for these reactions are discussed. The X-ray crystal structure of [[graphic omitted]CF₃}(O₂CCF₃)(NO)(PPh₃)₂]·CH₂Cl₂ has been determined. The crystals are triclinic, space group P, with a= 12.709(3), b= 22.694(8), c= 9.662(3)Å, α= 118.28(3), β= 113.59(3), γ= 59.66(4)°, and Z= 2. The structure has been refined to R(F)= 0.051 and R′(F)= 0.049 for 4 730 observed reflections. The complex contains six-co-ordinated osmium(II) bound to a chelate O,O′-trifluoroacetohydroximate(2–) ligand, a unidentate trifluoroacetate ligand, a linear nitrosyl group, and a pair of mutually cis triphenylphosphine ligands.