Influence of Pt—Cl force constants on the Raman lineshapes in Pt 35 Cl/ 37 Cl chains

The influence of the 35 Cl/ 37 Cl isotopic disorder of natural chlorine on the Raman and infrared lineshapes of the vibrational modes in PtCl chains was calculated as a function of the interionic force constants in a one‐dimensional model. It is shown that the fine structure of the Raman line is strongly dependent of the Pt 3+σ ‐Cl and Pt 3‐σ ‐Cl force constants, and so it can be used to estimate the charge disproportion σ. From the case of [Pt(en) 2 ][Pt(en) 2 Cl 2 ](ClO 4 ) 4 it appears that the description of the high‐wavenumber infrared line ( v 2 ) requires one to take into account interactions with more distantations. It is also shown that the intensity of the lowwavenumber infrared‐active mode ( v 3 ) is so weak that the corresponding line may have never been observed.