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 But), 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)A, 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.