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-AgLx)(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.