Infrared spectra, electronic spectra, and magnetic properties of dihalogenobis(pyrazine) complexes of cobalt(II) and nickel(II): a structural re-assignment

Abstract

Detailed studies have been made of the i.r. (to 80 cm^–1) and Raman spectra, and variable-temperature magnetic susceptibilities, of the complexes MX₂(pyrazine)₂[M = Co or Ni; X = Cl, Br, or I]. It is shown that the compounds are of sheet structure, having metal atoms linked by pyrazine bridges, with trans-terminal halogen atoms, rather than the halogen-bridged chain structure previously proposed. This has necessitated a re-interpretation of their electronic spectra.