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)A, and β= 102.50(2)°, and those for (2) are a= 8.520(3), b= 20.096(6), c= 12.747(4)A, 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an axial carbonyl on an adjacent Os atom to and on the opposite side of the Os3 plane from the co-ordinated nitrile has been replaced by the second NCMe ligand.