Metal complexes of azopyridines. Part III. Complexes of nickel(II) and copper(II) with 2,2′-azopyridine

Abstract

2,2′-Azopyridine has been used to form metal halide complexes of the types MX₂,2L, MX₂,L, MX₂,½L (M = Cu; X = Cl or Br; M = Ni; X = Cl) and NiCl₂,½L,H₂O; and metal sulphate complexes of the type MSO₄,½L,nH₂O (M = Cu, n= 1; M = Ni, n= 2). The results of i.r. (450–80 cm.^–1) and electronic spectral measurements suggest that in CuX₂,2L (X = Cl or Br) and in the complexes of nickel chloride and of both metal sulphates, the metal atoms are six-co-ordinate. For CuX₂,½L (X = Cl or Br) the low-frequency i.r. results are compatible with structures in which the azopyridine ligands bridge planar or tetrahedrally co-ordinated Cu₂X₄ units (the latter geometry being indicated by the electronic spectra), whereas CuX₂,L (X = Cl or Br) contain linear CuX₂ groupings linked by amine bridges.