Geometrical isomers of the capped octahedron in the solid state. Crystal and molecular structure of dibromodicarbonyltris(dimethyl-phenylphosphine) molybdenum(II)–acetone (1/1)

Abstract

Crystals of the title compound are monoclinic, space group P2₁ with a= 12.145(8), b= 11.789(10), c= 12.296(10)Å, β= 104.86(10)°, Z= 2. The intensities of 2 377 independent reflections above background were collected by counter methods and refined to R 0.062. The molecule is a seven-co-ordinate monomer in which the metal atom occupies a capped octahedral environment. A carbonyl group occupies the capping position [1.900(16)Å], three phosphorus atoms are in the capped face [2.586(5), 2.520(4), and 2.503(5)Å] and two bromine atoms [2.680(2) and 2.666(2)Å] and the remaining carbonyl group [2.026(25)Å] make up the uncapped face. The molecule is disordered with one site in the uncapped face, occupied by 87% carbonyl and 13% bromine. The arrangement of atoms in the co-ordination sphere is different from that found in the analogous dichloro-compound in which a carbonyl group occupies the capping position, two phosphorus atoms and carbonyl group the capped face, and two chlorines and a phosphorus atom the uncapped face.