Reaction of Ru 3{μ-H, μ-OCNMe 2}(CO) 10 with diarylacetylenes; synthesis and subsequent reaction of a {μ-carboxamido, μ-σ,π-vinyl}-hexacarbonyl diruthenium complex with propyne. Crystal and molecular structures of Ru 2{μ-OCNMe 2,μ-σ,π-C( p-tol)CH( p-tol)}(CO) 6, and of Ru 2{μ-OCNMe 2,μ-σ,π-C(CH 3)C(H)C( p-tolyl)CH( p-tolyl)}(CO) 6 ( p-tol = p-CH 3C 6H 4)

Abstract

The complex Ru 3{μ-OCNMe 2,μ-H}(CO) 10 ( 1) is observed to react with diphenylacetylene ( 2a), di( p-tolyl)acetylene ( 2b), or di( p-anisyl)acetylene ( 2c), at 23° C in hexane solution over a period of 12 h to give Ru 2{μ-OCNMe 2,μ-σ,π-C(Ar)CH(Ar)}(CO) 6, Ar = Ph ( 3a), p-CH 3C 6H 4 ( 3b), or p-CH 3OC 6H 4 ( 3c). Principal by-products are Ru 3(CO) 12 and the acetylene oligomerization complexes {η 5-(OC) 3 RuC(Ar)C(Ar)C(Ar)C (Ar)}Ru(CO) 3, Ar = C 6H 5 ( 4a), Ar = p-tolyl, CH 3C 6H 4 ( 4b), Ar = p-anisyl, CH 3OC 6H 4 ( 4c). Variable temperature 13C NMR of 3a, 3b, and 3c indicates the presence of two rapidly interconverting isomers in solution, one with geminal and the other with vicinal bridging groups. Complex 3b is observed to react with propyne at 23° C in hexane over a period of 4 h giving as principal product Ru 2{μ-OCNMe 2,μ-σ,π-C(CH 3)C(H)C( p-tolyl)CH( p-tolyl)}(CO) 6, 5. The crystal and molecular structures of 3b and 5 have been determined using graphite-monochromatized Mo- K α radiation on a Huber four circle diffractometer under control of a VAX 11/750 computer. Complex 3b crystallizes in the monoclinic space group P2 1/ a; cell dimensions a = 20.1744(23), b = 7.3166(8), c = 18.9413(22) Å, and β = 93.2730(31)° and Z = 4, V = 2786.12 Å 3; ρ(calc.) = 1.55 g cm −3. A total of 3923 unique reflections with I > 3σ( I) were used in the refinement; final discrepancy indices, R = 0.057 and R w = 0.071. The crystal consists of discrete molecules of the complex in which the metal-metal separation Ru(1)Ru(2) = 2.739(1) Å. The two bridging groups, namely {μ-σ,π-C(50)(Ar)C(40)H(Ar)} and {O(30)C(30)NMe 2}, are seen to be attached to the two metal centers in a vicinal arrangement with a near octahedral arrangement of σ-bonded atoms around each metal. Bond distance parameters for the bridging groups are (Å): Ru(2)O(30) = 2.117(5); O(30)C(30) = 1.283(8); Ru(1)C(30) = 2.106(7); Ru(1)C(50) = 2.324(7); Ru(1)C(40) = 1.410(9); Ru(2)C(50) = 2.081(7); C(40)C(50) = 1.410(9). Complex 5 crystallizes in the monoclinic space group P2 1/ c with cell dimensions: a = 10.421(4), b = 33.157(10), c = 8.896(3) Å, β = 90.34(3)° and Z = 4, V = 3078 Å 3; ρ(calc.) = 1.49 g cm −3. The structure was solved by the heavy atom method. A total of 3159 unique reflections with I > 3σ( I) were used in the refinement; final discrepancy indices, R F = 0.085 and R wF = 0.110. Complex 5 consists of two tricarbonyl ruthenium fragments joined by a strong RuRu bond, 2.726(2) Å, accompanied by a bridging carboxamido group and a bridging σ,π-group (C(CH 3)C(H)R (R = C( p-tolyl)C(H) p-tolyl) in a sigma-geminal arrangement. This type of complex is perceived as a common intermediate to the oligomerization products 4a, 4b, 4c observed in the present and previous studies, and the complex Ru 2{μ-OCNMe 2, μ-OCC(Me)CMe(η 2-CMeCHMe)}(CO) 5, observed in a previous study.