Complexes of the platinum metals. Part 31. Reactions of binuclear ruthenium(II,III) and rhodium(II) carboxylates with chelating diphosphines;X-ray crystal structure of (acetato-O,O′)bis[bis(diphenylphosphino)methane-P,P′]ruthenium(II) tetraphenylborate

Abstract

The chelating diphosphines Ph₂P(CH₂)_nPPh₂(n= 1–3) react with binuclear carboxylato complexes [Ru₂(O₂CR)₄Cl](R = Me, Et, or Ph) in cold or refluxing benzene to yield products trans-[Ru(O₂CR)₂{Ph₂P(CH₂)_nPPh₂}₂] and cis-[Ru(O₂CR)₂{Ph₂P(CH₂)_nPPh₂}₂] respectively, both of which are readily converted to the tetraphenylborate salts [Ru(O₂CR){Ph₂P(CH₂)_nPPh₂}₂]BPh₄. Attempts to obtain similar products using samples of [Ru₂(O₂CR)₄Cl](R = CF₃ or Bu^t), prepared from the corresponding acetate complex by treatment with the appropriate carboxylic acids under vigorous conditions, gave mixtures indicative of incomplete carboxylato exchange. The trans complexes [Ru(O₂CR)₂(Ph₂PCH₂PPh₂)₂] react with NaBH₄ and CO to afford cis- and trans-[RuH₂(Ph₂PCH₂PPh₂)₂] and cis,cis,trans-[ Ru(O₂CR)₂(CO)₂(Ph₂PCH₂PPh₂)₂] respectively. The latter species react with NaBH₄ to yield cis- and trans-[RuH₂(CO)(Ph₂PCH₂PPh₂)₂]. Several of these products contain pendant Ph₂PCH₂PPh₂ ligands. The corresponding complexes containing Ph₂P(CH₂)₂PPh₂ failed to carbonylate even under vigorous conditions. The relationship between chelate ring size and ³¹P n.m.r. parameters for some of these complexes is discussed. Confirmation that the cations contained in the tetraphenylborate salts are mononuclear and not, as previously suggested elsewhere, binuclear has been provided by an X-ray diffraction study of one such salt [Ru(O₂CMe)(Ph₂PCH₂PPh₂)₂]BPh₄. The crystals are triclinic, space group P(no. 2), with a= 14.693(5), b= 18.821(4), c= 11.807(3)Å, α= 95.39(2), β= 108.03(2), γ= 92.43(2)°, and Z= 2 at 144(2) K. The complex contains tris(chelate)ruthenium(II) cations with bidentate acetate and bis(diphenylphosphino)methane ligands together with tetraphenylborate anions.