Abstract
The resonance Raman and electronic spectra of compounds Ni(en)2X3, Ni(dapn)2X3 etc. and of compounds [Ni(en)2Pt(en)2X2](ClO4)4 (where X = Cl or Br) show that those are mixed valence compounds with a metal halide chain (en = 1,2-diaminoethane, dapn = 1,2-diaminopropane).