The geometries and energies of the ground singlet1A1and First excited triplet (3B1) states of SiCl2, SiBr2, GeCl2, and GeBr2and the ground states of their dimers were determined from ab initio Hartree-Fock calculations, in order to identify the additional component observed in the electron diffraction radial distribution of GeBr2. The results show that the triplet states of these molecules are 140–200 kJ/mol higher in energy than the singlet states and can be thus excluded as the additional component at the experimental temperature. The bridged dimer of GeBr2is calculated to be weakly bound and is predicted to be the additional component. We have calculated the force constants and fundamental frequencies of the singlet monomers. The latter, after the usual scaling, agree well with the experimental frequencies. A matrix-infrared study of the system could positively identify the dimer as the additional component, and the predicted vibrational fundamental frequencies of Ge2Br4are given to assist in this identification.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry