New compounds containing the triangulo-trichlorotrivanadium(II) moiety

The complex [VCl2(tmen)(2)] (tmen = N,N,N',N'-tetramethylethane-1,2-diamine) changes spontaneously into a triangulo-trinuclear species [V-3(mu-Cl)(3)(mu-Cl)(2)(tmen)(3)](+) in solution in tetrahydrofuran upon addition of salts of suitable counter ions. The apical (mu(3)) chlorides can be replaced by methoxide, and the tmen by diphosphines. Several related materials, all containing the triangulo-V3X3 (X = Cl or Br) motif, were characterised by mass spectroscopy, X-ray diffraction and other techniques. These clusters are antiferromagnetic both in solution and in the solid state. Thermogravimetric analysis of trans-[VCl2(tmen)(2)] and of [V(MeOH)(6)]Cl-2 implied the formation of similar triangulo-V3Cl3 species, which appear to be of common occurrence in vanadium(II) chemistry.