Cluster chemistry. Part 18. Isocyanide complexes derived from [Ru3(CO)12]: crystal and molecular structures of [Ru3(CO)12 –n(CNBut)n](n= 1 or 2)

Abstract

Reactions between [Ru₃(CO)₁₂] and isocyanides CNR have given the complexes [Ru₃(CO)_{12 –n}(CNR)_n](R = Bu^t, n= 1, 2, or 3; R = C₆H₁₁, n= 1; R = C₆H₄OMe-p, n= 1 or 2; and R = CH₂SO₂C₆H₄Me-p, n= 3) as orange to red crystalline solids. The crystal structures of [Ru₃(CO)_{12 –n}(CNBu^t)_n](n= 1 or 2) have been determined by X-ray diffraction studies, and refined to residuals of 0.035 (4 561 ‘observed’ reflections) and 0.043 (2 849 ‘observed’ reflections) respectively. Crystals of [Ru₃(CO)₁₁(CNBu^t)] are monoclinic, space group P2₁/c with a= 11.948(5), b= 12.108(4), c= 16.621(4)Å, β= 112.74(2)°, and Z= 4; crystals of [Ru₃(CO)₁₀(CNBu^t)₂] are monoclinic, space group P2₁/a with a= 11.910(10), b= 12.831(17), c= 9.565(16)Å, β= 111.84(10)°, and Z= 2. In the latter derivative, the ligand array is ‘centrosymmetric’ about a crystallographic special position, with the two isocyanide ligands in axial sites; the Ru₃ triangle is disposed about a pair of equally populated centrosymmetrically related dispositions within the ligand array. In [Ru₃(CO)₁₁(CNBu^t)] the isocyanide substituent is also axial; the Ru₃ triangle is similarly disordered but only to the extent of ca. 14% within the ligand array. A method for the almost quantitative conversion of RuCl₃·xH₂O to [Ru₃(CO)₁₂] has been developed consisting of carbonylation of 1% methanol solutions (50–60 atm CO, 125 °C, 16–18 h), recycling the mother-liquors with fresh RuCl₃·xH₂O.