Complexes of 2- and 4-vinylpyridines with cobalt(II) and nickel(II) halides and pseudohalides

Abstract

Complexes of cobalt(II) and nickel(II) with 2-vinylpyridine (2-vpy) and 4-vinylpyridine (4-vpy) exhibit various stereochemistries according to their stoicheiometry and the anion X present: octahedral, M(4-vpy)₄X₂(M = Co, Ni; X = Cl, Br, I, NCO, NCS); polymeric octahedral, M(4-vpy)₂X₂[M = Co, X = Cl (mauve-form), N₃; M = Ni, X = Cl, Br, N₃, NCS]; and tetrahedral, Co(4-vpy)₂X₂(X = Cl, Br, I) and Co(2-vpy)₂X₂(X = Cl, Br, I, NCS). Structures have been assigned from the electronic, i.r., and far-i.r. spectra, and magnetic behaviour of the complexes. In several cases the assigned structures have been confirmed by X-ray powder investigations. The complexes M(4-vpy)₂(N₃)₂ are antiferromagnetic while the complexes Ni(4-vpy)₂X₂(X = Cl, Br) are weakly ferromagnetic.