REACTIVITY OF [RU3H2(CO)9(MU-3-COME)(M(PPH3))] (M=CU, AG OR AU) AND [RU3H(CO)9(MU-3-PPH)(AG(PPH3))] WITH PPH3

Addition of PPh3 to [Ru3H2(CO)9(mu-3-COMe){Cu(PPh3)}] 1 results in rapid heteronuclear decapping to form the anion [Ru3H2(CO)9(mu-3-COMe)]-. A similar reaction occurs for the silver analogue 2 with excess of PPh3. However a 1:1 reaction mixture affords [Ag(PPh3)4][{Ru3H2(CO)9(mu-3-COMe)}2Ag] 5, which is stable in solution at low temperatures. NMR evidence is consistent with the anion having C2 symmetry in which an approximately tetrahedrally co-ordinated silver centre links the two triruthenium clusters by edge bridging to each cluster. Reaction of [Ru3H(CO)9(mu-3-PPh){Ag(PPh3)}] 4 with PPh3 (1:1) affords an equilibrium mixture (at 173 K) of [Ru3H(CO)9(mu-3-PPh)]-, 4, [Ag(PPh3)n]+ (n = 3 and 4) and [{Ru3H(CO)9(mu-3-PPh)}2Ag]-. All these reactions are faster than the carbonyl substitution reactions which occur at room temperature.