Quantum chemical predictions of vibrational mode analysis of germaformaldehyde and related molecules

Hybrid density functional theory and ab-initio methods have been evaluated as practical tools for calculations of infrared vibrational frequencies and absorption intensities of XGeWZ molecules (where X = O, S, Se; W, Z = H, F, Cl). The theoretical results have been compared with the most current experimental data. It shows that XGcWZ species have two states, namely singlet ((1)Sigma) state and triplet ((3)Sigma) state. We have found that the singlet ((1)Sigma) state of the species is more stable than the triplet ((3)Sigma) state. When different halogens combine to the central Ge atom, the bond length order is Ge-H < Ge-F < Ge-Cl, and the energy order is HGeXH > FGeXF > ClGeXCl (where X = O, S, Se). When element X alters, the bond length order is Ge=O < Ge=S < Ge=Se, and the energy order is WGeOZ < WGeSZ < WGeseZ. The orders of the bond angles are angle WGeO < angle WGeS < angle WGeSe and angle WGeZ (X=O) > angle WGeZ (X=S) > angle WGeZ (X=Se) (where W, Z = H, F, Cl). The vibrational frequencies and vibrational mode analysis are well agreeing with the optimized geometric results.