Complexes of the early transition-metal halides with tritertiary arsines

Abstract

The ligands bis-(o-dimethylarsinophenyl)methylarsine (o-TAS) and tris-1,1,1-(dimethylarsinomethyl)ethane (ν-TAS) react with titanium and vanadium tetrachlorides to yield monomeric, non-electrolytic complexes of the type [MCl₄,TAS], for which n.m.r. measurements demonstrate that all three arsenic atoms of each ligand are coordinated to the metal. The titanium and vanadium atoms in these complexes are therefore seven-co-ordinate. The complexes are rapidly hydrolysed in moist air, those of vanadium forming definite complexes of the type [VOCl₂,TAS].

The trihalides of vanadium and chromium react with the triarsines to form neutral monomeric complexes of the type [MCl₃,TAS], in which the ligands are again terdentate. The number of infrared-active metal–halogen stretching frequencies indicates that, for all complexes of this type, the halogen atoms (and therefore the arsenic atoms also) are vicinal. Surprisingly, under the conditions employed, titanium trichloride does not react with either of the triarsines to form complexes of this type.

The electrical conductivities, molecular weights, magnetic moments, infrared spectra (4000–200 cm.^–1), and electronic and n.m.r. spectra of the complexes have been recorded, where possible, and are discussed in detail in order to provide the requisite structural information.