Reaction of Polynuclear Acetylide Clusters. Mixed-Metal Complexes Derived from Reactions of CpWos₃(CO)₁₁(C=CR) (R = Ph, ⁿBu) with Disubstituted Alkynes

Reaction of CpW(CO)₃(C≡CR) with Os₃(CO)₁₀(CH₃CN)₂ in refluxing toluene produces tetranuclear mixed-metal acetylide complexes, CpWOs₃(CO)₁₁(C≡CR) (R = Ph (1a), ⁿBu (1b)). Reaction of 1a with excess ditolylacetylene in refluxing toluene effects the scission of acetylide ligand to give CpWOs₃-(CO)₈(µ₃-CPh)[µ⁴-η⁵-C(C₂Tol₂)₂] (3). In contrast, treatment of complexes 1a and 1b with alkynes containing electron-withdrawing groups produces the tetranuclear alkyne-acetylide coupling products CpWOs₃-(CO)₁₀[CR′CR′CCR] (R = Ph, R′ = CO₂Me (4a), CO₂Et (4b); R =ⁿBu, R′ = CO₂Et (4c)) and CpWOs₃-(CO)₉[CCRCR′CR′] (R = Ph, R′ = CO₂Me (5a), CO₂Et (5b); R =ⁿBu, R′ = CO₂Et (5c)). The structures of complexes 1a, 3, 4c, and 5a have been determined by single-crystal X-ray diffraction studies. Crystal data for 1a: space group P2₁/c; a = 9.057 (2), b = 9.197 (1), c = 29.065 (4) Å; β = 95.77 (1)°; Z-4; final R-0.055, R_w- 0.060, and GOF = 2.757. Crystal data for 3: space group PI; a = 10.351 (3), b = 12.576 (3), c = 18.098 Å; α = 94.44 (2), β = 91.07 (2), γ = 96.00 (2)°; Z = 2; final R = 0.041, R_w= 0.042, and GOF = 2.397. Crystal data for 4c: space group P2₁/n; a = 10.025 (2), b = 9.550 (5), c = 34.708 Å; β = 91.19 (2)°; Z = 4; final R = 0.070, Rw = 0.072, and GOF = 2.77. Crystal data for 5a: space group PI; a = 9.203 (3), b = 11.580 (3), c = 14.937 Å; α = 91.57 (2), β = 100.85 (2), γ-102.23 (2)°; Z = 2; final R = 0.033, R_w= 0.034, and GOF = 1.928.