Reactions of Tertiary Amines with Trinuclear Clusters. 3.^† Reactions of N-Methylpyrrolidine with Ru₃(CO)₁₂ and Os₃(CO)₁₀(CH₃CN)₂

The reaction of N-methylpyrrolidine with Ru₃(CO)₁₂ in the presence of the three reaction promoters Fe₂(CO)₄(μ-SCH₂CH₃)₂(P(C₆H₅)₃)₂ (iron dimer), (CH₃)₃NO, and (C₆H₅)₂C = O⁻Na⁺ was studied in the temperature range 65–80 °C. In the presence of the iron dimer catalyst, in hexane at 68 °C, one major trinuclear product isolated in 15–20% yield proved to be (μ-H)₂Ru₃(CO)₉(μ₃-η²-CH-N=CCH₂CH₂CH₂) (1). In the presence of trimethylamine N-oxide or sodium benzophenone ketyl in benzene at 80 °C a different trinuclear product isolated in 30% yield, (μ-H)Ru₃(CO)₉(μ₃-η²-N=CCH₂CH₂CH₂) (2), is a structural analogue of the major product obtained from the reaction of triethylamine with Ru₃(CO)₁₂ in the presence of the above mentioned diiron reaction promoter. A minor product isolated in the reaction of Ru₃(CO)₁₂ with N-methylpyrrolidine in the presence of (CH₃)₃NO is the tetranuclear η¹-carbene species (μ-H)₄Ru₄-(CO)₁₁(η¹-C=N(CH₃)CH₂CH₂CH₂) (3). Thermolysis of 1 in heptane at 100 °C gave moderate yields of the compound (μ-H)Ru₃(CO)₉(μ₃-η³-CH₃N-CH=CHCH₂CH₂) (4), in which two hydrogens have been transferred to the methyne carbon and further rearrangement of the ligand has occurred. The lightly stabilized cluster Os₃(CO)₁₀(CH₃CN)₂ was reacted with N-methylpyrrolidine in refluxing benzene to give (μ-H)Os₃(CO)₁₀(μ-η²-CH₃N=CC(H)CH₂CH₂) (5) and (μ-H)Os₃(CO)₁₀(μ-η¹-CH₃N=C(H)CCH₂CH₂) (6). Compounds 1–5 were characterized by X-ray diffraction methods in the solid state, and 1–6, by ¹H NMR and infrared spectroscopy in solution. Compound 1 crystallizes in the monoclinic space group P2₁/n, with a = 9.015 (2) Å, b = 16.759 (4) Å, c = 13.266 (3) Å, and β = 95.98 (2)°. Least-squares refinement of 3822 observed reflections gave a final agreement factor of R = 0.048 (R_w = 0.055). Compound 2 crystallizes in the monoclinic space group P2₁/m, with a = 7.657 (1) Å, b = 14.910 (3) Å, c = 8.172 (2) Å, and β = 106.32 (2)°. Least-squares refinement of 1938 observed reflections gave a final agreement factor of R = 0.026 (R_w = 0.031). Compound 3 crystallizes in the monoclinic space group P2₁/c, with a = 10.198 (1) Å, b = 14.229 (2) Å, c = 16.512 (3) Å, and β = 102.34 (1)°. Least-squares refinement of 2033 observed reflections gave a final R = 0.025 (R_w = 0.036). Compound 4 crystallizes in the monoclinic space group P2₁/c, with a = 8.858 (2) Å, b = 13.455 (5) Å, c = 18.400 (4) Å, and β = 118.70 (2)°. Least-squares refinement of 2254 observed reflections gave a final R = 0.043 (R_w = 0.045). Compound 5 crystallizes in the orthorhombic space group P2₁2₁2₁, with a = 11.567 (2) Å, b = 17.653 (6) Å, and c = 9.900 (2) Å. Least-squares refinement of 2600 observed reflections gave a final R = 0.074 (R_w = 0.065).