CLUSTER CHEMISTRY .91. CLUSTERS DERIVED FROM 1,4-BIS(DIPHENYLPHOSPHINO)BUTA-1,3-DIYNE AND THEIR PYROLYSIS PRODUCTS - A ROUTE TO COMPLEXES CONTAINING THE TETRACARBON LIGAND

Reactions of (Mn(CO)11(NCMe)] (M(n) = Ru3, Os3, Re3(mu-H)3, or Ru4(mu-H4)4] with the linear bis(phosphine) PPh2C2C2PPh2(bdpp) afford the 'barbell' complexes [{Mn(CO)11}2(mu-bdpp)] [M(n) = Ru3 1 (38), Os3 2 (68), Re3(mu-H), 4 (44), or Ru4(mu-H)4 6 (39%)]. The monosubstituted complexes [Mn(CO)11(bdpp)] [M(n) = Os3 or Re3(mu-H)3 5] were isolated when an excess of bdpp was used. Reactions of 3 with [M3(CO)11(NCMe)] [M3 = Ru3 or Re3(mu-H)3] afforded the mixed-metal complexes [{Os3(CO)11}(mu-bdpp){M3(CO)11}] [M3 = Ru 7 (40) or Re3(mu-H)3 8 (63%)]. In a similar fashion [{Re3(mu-H)3(CO)11)(mu-bdpp){Ru3(CO)11}] 9 was prepared (38%) from 5 and [Ru3(CO)11(NCMe)]. When a solution of 1 in CH2Cl2 was gently heated under a nitrogen purge the C4 complex [{Ru3(mu-PPh2)(CO)9}2(mu3:mu3-C4)] 10 was produced in 73% yield. Without purging, the yield is much reduced; a minor product from the reaction is [{Ru4(mu-H)(CO)12}{mu4-PPh(C6H4)C2C2PPh2}{Ru3(CO)11}] 11. Complex 11 contains an Ru3(CO)11 moiety linked via a PPh2C2C2PPh(C6H4) ligand to an Ru3-spiked RU3 Cluster. One of the C2 units is attached in a mu-sigma,sigma,eta2-vinylic mode to the spike Ru and to two of the three Ru atoms in the closed triangular core. When 11 was recrystallised from CH2Cl2-MeOH the complex [{Ru4(mu3-OMe)(mu-PPh2)(CO)10}{mu4-CCH-mu-eta2-C2){RU2(mu-PPh2)(CO)6}] 12 was formed. This complex contains an Ru4 rhombus, opposite faces of which carry mu3-OMe and a mu4-vinylidene ligand; the latter is attached via a C-C single bond to the binuclear fragment. The complex [{Os3(mu-PPh2)(CO)9}2(mu3:mu3-C4)] 13 was obtained (78%) by pyrolysis of 2 in refluxing toluene. The structures of complexes 6 and 10-13 were determined by single-crystal X-ray studies.