Ruthenium complexes containing Group 5B donor ligands. Part 3. Rearrangement reactions of some ruthenium(II) carbonyl and thiocarbonyl triphenylphosphine complexes

Abstract

Reaction of [RuCl₂(PPh₃)₃] with [Ru(CO)Cl₂(dmf)(PPh₃)₂] in acetone (1: 1 molar ratio)(dmf =NN-dimethylformamide) gives a high yield of [(Ph₃P)₂ClRuCl₃Ru(CO)(PPh₃)₂]·2Me₂CO, supporting the mechanism proposed earlier for formation of the analogous thiocarbonyl complex. Extensions of this type of coupling reaction to form [(Ph₃P)₂BrRuBrCl₂Ru(CO)(PPh₃),]·Me₂CO and [(Ph₃P)₂ClRuBr₂ClRu(CO)(PPh₃)₂]·Me₂CO are also described. Recrystallisation of [Ru(CO)Cl₂(dmf)(PPh₃)₂] from MaOH–CH₂Cl₂ gives [Ru(CO)Cl₂(HOMe)(PPh₃)₂](4), and prolonged refluxing of the latter in dichloromethane–light petroleum (b.p. 60–80 °C) produces displacement of a PPh₃ group with formation of an isomeric mixture of [(Ph₃P)Cl(OC)RuCl₃Ru(CO)(PPh₃)₂](5). The same isomeric mixture, together with [{Ru(CO)Cl₂(PPh₃)₂}₂], is also formed by reaction of PPh₃ with [PPh₃(CH₂Ph)][Ru(C₇H₈)(CO)Cl₃](2 : 1 molar ratio). Treatment of (5) with Na[BPh₄] and PPh₃ in CH₂Cl₂ gives a high yield of [(Ph₃P)₂(OC)RuCl₃Ru(CO)(PPh₃)₂][BPh₄](6). This cation is also formed, together with (5), by prolonged shaking of (4) in ethanol, whereas treatment of (4) with [AsPh₄]Cl·HCl in acetone gives [AsPh₄][Ru(CO)Cl₃(PPh₃)₂]·Me₂CO (7). Related complexes are described, starting from [Ru(CS)Cl₂(dmf)(PPh₃)₂]. Finally, all this information is used to suggest detailed rearrangement mechanisms in the [RuCl₂(PPh₃)₃]–CS₂, [PPh₃(CH₂Ph)][Ru(C₇H₈)(CO)Cl₃]–2PPh₃, and the closely related [RuX₂(PR₃)_n]–[Ru₂X₃(PR₃)₆]X (X = Cl or Br; n= 3 or 4) systems.