Reactions of H2Os3(CO)10, 3, with the monophosphite‐substituted and non‐substituted tungsten propargyl and allenyl carbonyl complexes Cp(CO)2LWCH2C≡CH (1a, L = CO; 1b, L = P(OMe)3) and Cp(CO)2LWCH = C = CH2 (2a, L = CO; 2b, L = P(OMe)3) were investigated. In the reaction of 1b with 3, a tetranuclear complex 4b is obtained. The molecules of 4b crystallize as Cp(CO)2[P(OMe)3]W(μ, η1, η2‐CH2CH=CH)(μ‐H)Os3(CO)l0 in space group PI with a = 9.490 (4), b = 13.072 (7), c = 13.770 (9) Å, α = 91.89 (5), β = 106.71 (5), γ = 104.07(4)°, V = 1577(2) Å3, Z = 2. In the reaction of 2a with 3, from the reaction mixture exposed to air followed by workup using silica‐gel packed column chromatography, a complex consisting of two triosmium clusters bridged by a hexadiene ligand from the coupling of allenyl ligand was obtained. The molecules of the hexanuclear complex crystallize as [CH2CH = CH)2(μH)2OS6(CO)20in space group P21/c with a = 14.448 (7), b = 13.689 (4), c = 19.224 (4) Å, β = 107.14(3)°, V = 3633 (2) Å Z = 4.