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.