Complexes of vanadium(II) with heterocyclic and aliphatic amines

Abstract

Complexes of vanadium(11) with a range of heterocyclic and aliphatic amines have been isolated, generally from ethanolic solution under nitrogen. With pyridine (py) and β- and γ-picolines (β pic and γ pic) complexes of the general formula V(amine)4X2, in which X = Cl, Br, or I, have been obtained. Their reflectance spectra are dominated by charge transfer bands, but some d-d transitions have been assigned. These complexes are magnetically dilute with magnetic moments near to 3.87 B.M. The only bis(amine) complexes isolated with these ligands are V(β pic),Br, and V(γ pic)2Br2, and these show considerable antiferromagnetic interaction because of polymeric structures. The thermal behaviour of the complexes V(amine)4X2 resembles that of the corresponding nickel(11) complexes. No definite assignments of V-X stretching frequencies have been possible. With ethylenediamine (en), propane-1,2-diamine (α pda), propane-1,3-diamine (β pda) and diethylenetriamine (dien) the following magnetically dilute complexes have been isolated : [V(en)3] X2, [V(αpda)3] X2, [V(βpda)3] X2 and [V(dien)2] X2. These complexes with aliphatic chelates have electronic spectra typical of octahedral vanadium(11). The 8-aminoquinoline (amq) complexes, V(amq)2Cl2,- 2H20, V(amq)2Br2,2H2O and V(amq)3I2,2H20, have more complicated electronic spectra and are magnetically dilute as are some 1,l0-phenanthroline and 2,2'-bipyridyl complexes of general type [V(chelate)3] X2,nH2O.