Crystal and molecular structures of [Os3(CO)11(NCMe)] and [Os3(CO)10(NCMe)2]

Abstract

Both the complexes [Os₃(CO)₁₁(NCMe)](1) and [Os₃(CO)₁₀(NCMe)₂](2) crystallise in the monoclinic space group P2₁/n with Z= 4. The cell parameters for (1) are a= 8.284(3), b= 14.787(5), c= 15.944(6)Å, and β= 102.50(2)°, and those for (2) are a= 8.520(3), b= 20.096(6), c= 12.747(4)Å, and β= 108.77(2)°. The structures have been solved by a combination of direct methods and Fourier-difference techniques, and refined by blocked-cascade least squares to R values of 0.039 for 1 459 diffractomer data, for (1), and 0.046 for 2 397 diffractometer data, for (2). The three Os atoms in (1) define an isosceles triangle. Two of the metal atoms are co-ordinated to two axial and two equatorial terminal carbonyl groups. The third Os atom is co-ordinated to one axial and two equatorial carbonyls and the second axial site is occupied by a linear nitrile ligand. The structure of (2) resembles that of (1) except that an axial carbonyl on an adjacent Os atom to and on the opposite side of the Os₃ plane from the co-ordinated nitrile has been replaced by the second NCMe ligand.