Reaction of [Ru 3(CO) 12] with tri(2-furyl)phosphine: Di- and tri-substituted triruthenium and phosphido-bridged diruthenium complexes

Abstract

Reaction of [Ru 3(CO) 12] with tri(2-furyl)phosphine, P(C 4H 3O) 3, at 40 °C in the presence of a catalytic amount of Na[Ph 2CO] furnishes two triruthenium complexes [Ru 3(CO) 10{P(C 4H 3O) 3} 2] ( 1) and [Ru 3(CO) 9{P(C 4H 3O) 3} 3] ( 2) with the ligand coordinated through the phosphorus atom. Treatment of 1 and 2 with Me 3NO at 40 °C affords the dinuclear phosphido-bridged complexes [Ru 2(CO) 6(μ-η 1,η 2-C 4H 3O){μ-P(C 4H 3O) 2}] ( 3) and [Ru 2(CO) 5(μ-η 1,η 2-C 4H 3O){μ-P(C 4H 3O) 2}{P(C 4H 3O) 3}] ( 4), respectively, that are formed via phosphorus–carbon bond cleavage of a coordinated phosphine followed by coordination of the dissociated furyl moiety to the diruthenium center in a σ,π-alkenyl mode. Reaction of [Ru 3(CO) 12] with tri(2-furyl)phosphine in refluxing benzene gives, in addition to 3 and 4, low yields of the cyclometallated complex [Ru 3(CO) 9{μ-η 1,η 1-P(C 4H 3O) 2(C 4H 2O)} 2] ( 5). Treatment of 3 with EPh 3 (E = P, As, Sb) at room temperature yields the monosubstituted derivatives [Ru 2(CO) 5(μ-η 1,η 2-C 4H 3O){μ-P(C 4H 3O) 2}(EPh 3)] (E = P, 8; E = As, 9; E = Sb, 10). Similar reactions of 3 with P(C 4H 3O) 3, P(OMe) 3 and Bu t NC yield 4, [Ru 2(CO) 5(μ-η 1,η 2-C 4H 3O){μ-P(C 4H 3O) 2}{P(OMe) 3}] ( 11) and [Ru 2(CO) 5(μ-η 1,η 2-C 4H 3O){μ-P(C 4H 3O) 2}(NCBu t )] ( 12), respectively. The molecular structures of complexes 3, 4 and 8 have been elucidated by single crystal X-ray diffraction studies. Each complex contains a bridging σ,π-alkenyl group and while in 4 the phosphine is bound to the σ-coordinated metal atom, in 8 it is at the π-bound atom. Protonation of 3 and 4 gives the hydride complexes [(μ-H)Ru 2(CO) 6(μ-η 1,η 2-C 4H 3O){μ-P(C 4H 3O) 2}] + ( 6) and [(μ-H)Ru 2(CO) 5(μ-η 1,η 2-C 4H 3O){μ-P(C 4H 3O) 2}{P(C 4H 3O) 3}] + ( 7), respectively, while heating 3 with dimethylacetylenedicarboxylate (DMAD) in refluxing toluene gives the cyclotrimerization product, C 6(CO 2Me) 6.