Crystal and molecular structure of tri-µ-chloro-bis[dicarbonylbis(trimethyl phosphite)molybdenum] tetrachloro(dimethyl phosphito)oxomolybdate

Abstract

Crystals of the title compound are triclinic, space group P, with a= 11.714(13), b= 15.493(12), c= 15.038(13)A, α= 117.06(10), β= 99.43(11), γ= 96.96(14)°, Z= 2. The structure was determined from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares techniques to R 0.077, for 3 066 observed reflections. While both cation and anion are in general positions, the cation has approximate C2v(mm) symmetry. The two molybdenum atoms in the cation are both seven-co-ordinate each being bonded to three bridging chlorines [2.533(7), 2.551(4), 2.549(6); 2.551(6). 2.538(6), 2.564(6)A], to two carbonyls [1.94(2), 1.91(2); 1.92(2), 1.92(2)A] and to two phosphorus atoms of trimethyl phosphite ligands [2.402(8), 2.438(6); 2.428(5), 2.420(7)A]. The geometry of the co-ordination sphere of both metal atoms is a (4 : 3) tetragonal base-trigonal base with the three chlorines in the trigonal base shared by both metal atoms. At least one of the twelve methoxy-groups is disordered. In the anion the metal atom is octahedral being bonded to a terminal oxygen [1.60(2)A], four chlorine atoms [2.369(8), 2.375(8), 2.376(8). 2.350(8)A], and an oxygen [2.18(2)A] of an oxydimethoxyphosphine group. This ligand, apart from the oxygen atom bonded to the metal, is disordered between two possible sites, with occupancy ratio ca. 2 : 1.