Cluster chemistry. Part 91. Clusters derived from 1,4-Bis (diphenylphosphino)buta-1,3-diyne and their pyrolysis products: a route to complexes containing the tetracarbon ligand

Abstract

Reactions of [Mn(CO)11(NCMe)][Mn= Ru3, Os3, Re3(µ-H)3, or Ru4(µ-H4)4] with the linear bis(phosphine) PPh2C2C2PPh2(bdpp) afford the ‘barbell’ complexes [{Mn(CO)11}2(µ-bdpp)][Mn= Ru31(38), Os32(68), Re3(µ-H)34(44), or Ru46(39%)]. The monosubstituted complexes [Mn(CO)11(bdpp)][Mn= Os33 or Re3(µ-H)35] were isolated when an excess of bdpp was used. Reactions of 3 with [M3(CO)11(NCMe)][M3= Ru3 or Re3(µ-H)3] afforded the mixed-metal complexes [{Os3(CO)11}(µ-bdpp){M3(CO)11}][M3= Ru 7(40) or Re3(µ-H)38(63%)]. In a similar fashion [{Re3(µ-H)3(CO)11}(µ-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(µ-PPh2)(CO)9}2(µ3:µ3-C4)]10 was produced in 73% yield. Without purging, the yield is much reduced; a minor product from the reaction is [{Ru4(µ-H)(CO)12}{µ4-PPh(C6 H4)C2C2PPh2}{Ru3(CO)11}]. 11. Complex 11 contains an Ru3(CO)11 moiety linked via a PPh2C2C2PPh(C6H4) ligand to an Ru-spiked Ru3 cluster. One of the C2 units is attached in a µ-σ,σ,η2-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(µ3-OMe)(µ-PPh2)(CO)10}(µ4-CCH-µ-η2-C 2){Ru2(µ-PPh2)(CO)6}]12 was formed. This complex contains an Ru4 rhombus, opposite faces of which carry µ3-OMe and a µ4-vinylidene ligand; the latter is attached via a C–C single bond to the binuclear fragment. The complex [{Os3(µ-PPh2)(CO)9}2(µ3:µ3-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.