Reaction of [Ru 3 (CO) 12 ] with tri(2-furyl)phosphine, P(C 4 H 3 O) 3 , at 40°C in the presence of a catalytic amount of Na[Ph 2 CO] furnishes two triruthenium complexes [Ru 3 (CO) 10 {P(C 4 H 3 O) 3 } 2 ] (1) and [Ru 3 (CO) 9 {P(C 4 H 3 O) 3 } 3 ] (2) with the ligand coordinated through the phosphorus atom. Treatment of 1 and 2 with Me 3 NO at 40°C affords the dinuclear phosphido-bridged complexes [Ru 2 (CO) 6 (μ-η 1 ,η 2 -C 4 H 3 O){μ-P(C 4 H 3 O) 2 }] (3) and [Ru 2 (CO) 5 (μ-η 1 ,η 2 -C 4 H 3 O){μ-P(C 4 H 3 O) 2 }{P(C 4 H 3 O) 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 4 H 3 O) 2 (C 4 H 2 O)} 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 4 H 3 O){μ-P(C 4 H 3 O) 2 }(EPh 3 )] (E=P, 8; E=As, 9; E=Sb, 10). Similar reactions of 3 with P(C 4 H 3 O) 3 , P(OMe) 3 and Bu t NC yield 4, [Ru 2 (CO) 5 (μ-η 1 ,η 2 -C 4 H 3 O){μ-P(C 4 H 3 O) 2 }{P(OMe) 3 }] (11) and [Ru 2 (CO) 5 (μ-η 1 ,η 2 -C 4 H 3 O){μ-P(C 4 H 3 O) 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 4 H 3 O){μ-P(C 4 H 3 O) 2 }] + (6) and [(μ-H)Ru 2 (CO) 5 (μ-η 1 ,η 2 -C 4 H 3 O){μ-P(C 4 H 3 O) 2 }{P(C 4 H 3 O) 3 }] + (7), respectively, while heating 3 with dimethylacetylenedicarboxylate (DMAD) in refluxing toluene gives the cyclotrimerization product, C 6 (CO 2 Me) 6 .