Crystal and molecular structures of the trimethylamine complexes of titanium tribromide and chromium trichloride

Abstract

The crystal structures of the complexes TiBr₃(NMe₃)₂ and CrCl₃(NMe₃)₂ have been determined from photographically collected X-ray diffraction data and refined to R 0·104 (565 reflections) and 0·064 (492 reflections). The molecules are monomeric and five-co-ordinate, possessing basically trigonal bipyramidal geometry. There are however deviations from the idealized trigonal symmetry of the equatorial group of halogen atoms and these can be related to the electron configuration. It is suggested that in these and related complexes of the type MX₃(AMe₃)₂, A = N or P, the ligand imposes the basic trigonal bipyramidal geometry of the co-ordination polyhedron.