Novel osmium N-oxide complexes from the reaction of triosmium clusters with 1-hydroxybenzotriazole

Article abstract of DOI:10.1021/om00020a033

Reaction of Os₃(CO)₁₀(NCMe)₂ (1) with 1-hydroxybenzotriazole (2) gave the hydrido complex (μ-H)Os₃(CO)₁₀(μ₂-(2,3-η ²)-NNN(O)C₆H₄) (3) in 60% yield; reaction of isocyanide complexes Os₃(CO)₁₀(CNR)(NCMe) (4: R = n-Pr, CH₂Ph) with 2 gave the bridging aminocarbyne products Os₃(CO)₁₀(μ₂-(2,3-η ²)-NNN(O)C₆H₄)(μ₂-η ¹-C=NHR) (5 and 6). The O-H bond of the hydroxybenzotriazole ligand was cleaved in these reactions to afford complexes 3, 5, and 6, which contained an N-oxide moiety. Complexes 5a and 6a as well as 5b and 6b were regioisomers because of the restricted rotation about the C=N double bond in the bridging aminocarbyne. These isomers exhibited different polarities and were separated by chromatography. Results from single-crystal X-ray diffraction analyses for 3, 5a, and 6b revealed the following data. 3: P2₁/c; a = 8.629(1) A?, b = 9.919(1) A?, c = 25.446(2) A?; β = 95.447(9)° V = 2168.1(3) A?³, Z = 4, R = 2.7%, R_w = 3.0%. 5a: P2₁/c; a = 10.4824(6) A?, b = 15.765(2) A?, c = 16.001(3) A?; β = 97.981(9)°, V = 2618.6(6) A?³, Z = 4, R = 3.0%, R_w = 3.7%. 6b: P2₁/c; a = 9.997(2) A?, b = 23.639(4) A?, c = 12.636(2) A?; β = 111.37(1)°, V = 2780.8(8) A?³, Z = 4, R = 2.9%, R_w = 3.1%. Studies on the structures of 5a and 6b by X-ray methods provided the first evidence indicating the existence of regioisomers with different orientations of the coordinated aminocarbyne group.