Density functional study of n-propyltrichlorogermane and n-propyltrichlorostannane

The IR and Raman spectra of n-propyltrichlorogermane (PTCG), CH3CH2CH2GeCl3, and n-propyltrichlorostannane (PTCS), CH3CH2CH2SnCl3, were measured in the liquid and solid states. The fundamental vibrations were assigned with the aid of a density functional theory (DFT) method using GAUSSIAN 98. For the calculation of the DFT method, the B3LYP/6-31G* and the 6-311 þ G** levels were used for C, H, Cl and Ge atoms and the B3LYP/CEP-31G level for Sn atom. The trans (T) and gauche (G) forms around the central C–C bond coexisted in the liquid state for both the molecules. While, the T form existed in the solid state for PTCG and the G form existed for PTCS. From the temperature dependent measurements of the Raman spectra in the liquid state, the enthalpy differences were found to be DHðG 2 TÞ ¼ 0:26 ^ 0:03 kcal mol21 with the T form being more stable for PTCG and to be DHðG 2 TÞ ¼ 20:03 ^ 0:01 kcal mol21 with the G form being slightly stable for PTCS, respectively. However, the energy differences between the forms calculated by the DFT method showed that the T form was more stable than the G form for both the molecules. q 2004 Elsevier B.V. All rights reserved.