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

Reaction of [Ru2(mu-CO)(CO)4{mu-(RO)2PN(Et)P(OR)2}2] (R = Me or Pr(i)) 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 substrates are co-ordinated either terminally as in [Ru2(sigma-HgCl)(CO)5{mu-(RO)2PN(Et)P(OR)2}2]+ or in the bridging mode as in [Ru2{mu-Au(PPh3)}-(mu-CO)(CO)4{mu-(RO)2PN(Et)P(OR)2}2]+ and [Ru2(mu-AgLx)(mu-CO)(CO)4{mu-(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(mu-CO)(CO)4{mu-(RO)2PN(Et)P(OR)2}2] and the solvento species [Ru2(CO)5(solv){mu-(RO)2PN(Et)P(OR)2}2]2+ thereby establishing that the formation of [Ru2(CO)5(solv){mu-(RO)2PN(Et)P(OR)2}2]2+ by treatment of [Ru2(mu-CO)(CO)4{mu-(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){mu-(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 tetrahydrothiophene, and halide, thiocyanate, benzenethiolate, trifluoroacetate, acetate and hydride ions. The crystal structures of [Ru2{mu-Au(PPh3)}(mu-CO)(CO)4{mu-(MeO)2PN(Et)P(OMe)2}2]SbF6, [Ru2(CO)5(PhCN){mu-(PriO)2PN(Et)P(OPri)2}2][SbF6]2 and [Ru2(CO)5(SC4H8){mu-(PriO)2PN(Et)P(OPri)2}2][SbF6]2 have been determined.