Reactions of diphosphazane-bridged derivatives of diruthenium nonacarbonyl with metal-containing electrophiles: formation of solvento species [Ru2(CO)5(solv){µ-(RO)2PN(Et)P(OR)2}2]2+(R = Me or Pri) and their reactivity towards various nucleophiles

Abstract

Reaction of [Ru₂(µ-CO)(CO)₄{µ-(RO)₂PN(Et)P(OR)₂}₂](R = Me or Prⁱ) with equimolar quantities of metal-containing electrophiles such as [AuCl(PPh₃)], silver(I) salts, [Cu(MeCN)₄]PF₆ and HgCl₂ has afforded cationic products in which the metal substrate are co-ordinated either terminally as in [Ru₂(σ-HgCl)(CO)₅{µ-(RO)₂PN(Et)P(OR)₂}₂]⁺ or in the bridging mode as in [Ru₂{µ-Au(PPh₃)}(µ-CO)(CO)₄{µ-(RO)₂PN(Et)P(OR)₂}₂]⁺ and [Ru₂(µ-AgL_x)(µ-CO)(CO)₄{µ-(RO)₂PN(Et)P(OR)₂}₂]⁺(L = pyridine or MeCN, x= 1 or 2). The silver adducts readily rearrange in solution with the nature of the product(s) formed being dependent on the identity of the ligand L and/or the solvent employed For non-protic weakly co-ordinating ligands such as acetonitrile, the silver-bridged cations disproportionate in solution to the parent compound [Ru₂(µ-CO)(CO)₄{µ-(RO)₂PN(Et)P(OR)₂}₂]and the solvento species [Ru₂(CO)₅(Solv){µ-(RO)₂PN(Et)P(OR)₂}₂]²⁺ thereby establishing that the formation of [Ru₂-(CO)₅(Solv){µ-(RO)₂PN(Et)P(OR)₂}₂]²⁺ by treatment of [Ru₂(µ-CO)(CO)₄{µ-(RO)₂PN(Et)P(OR)₂}₂] with a two-fold molar amount of silver(I) ions in non-protic weakly co-ordinating solvents occurs via an inner-sphere mechanism. In the case of the aqua and acetone solvento species [Ru₂(CO)₅(solv)-{µ-(RO)₂PN(Et)P(OR)₂}₂]²⁺(solv = H₂O or Me₂CO), both the solvent molecule and the carbonyl groups are labile with one or both being readily displaced by a wide range of neutral and ionic nucleophiles including carbon monoxide, isonitriles, nitriles, pyridine, 4,4′-bipyridine, dimethyl sulfide and tetra-hydrothiophene, and halide, thiocyanate, benzenethiolate, trifluoroacetate, acetate and hydride ions. The crystal structures of [Ru₂{µ-Au(PPh₃)}(µ-CO)(CO)₄{µ-(MeO)₂PN(Et)P(OMe)₂}₂]SbF₆, [Ru₂-(CO)₅(PhCN){µ-(PrⁱO)₂PN(Et)P(OPrⁱ)₂}₂][SbF₆]₂ and [Ru₂(CO)₅(SC₄H₈){µ-(PrⁱO)₂PN(Et)P(OPrⁱ)₂};₂]-[SbF₆]₂ have been determined.