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en)2M(IV)(en)2X2](C104)4, where X = CI or Br, M = Pt or Pd and en = ethylenediamine, show strong resonance enhancement of the . . .X-M(IV)-X.. . symmetric stretching vibration in the chain. Analysis of the spectra shows that the metals are coupled in the chain through the halide atoms. The coupling occurs by electron charge transfer via the d,z-orbitals of the metal from the lower to the higher oxidation state.

Abstract The electronic and resonance Raman spectra of new mixed-valence compounds of the type M2ʹ[M(L)X3][M(L)X5], where Mʹ = K, NH4, M = Pt or Pd, L = NH3 or pyridine, and X = Cl, Br or I, have been studied. The single-crystal polarized reflectance spectra indicate the one-dimensional semiconductor behaviour. The polarized resonance Raman spectra confirm the --M(II)--X-M(IV)-X linear chain structure, which is in accordance with the X-ray results. The polarization of M-N bands can be explained by the Snyder's theory (1971).

Abstract Some new mixed valence compounds of the type [M(L-L)2M(L-L)2X2]Y4 (where M = Pt or Pd, L-L = 2NH3 or ethylenediamine, X = Cl, Br or I and Y = HSO4, 1/2 SO4, ClO4 or 1/2 PtCl4) have been synthesized. The polarized Raman spectra of single crystals show the anisotropic character and the presence of ---M(II)---X-M(IV)-X chains. The method of preparation and the chemical behaviour correspond to the mechanism of the formation of Magnus green salt oxidized product.

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