Molecular structure and thermochemistry of tin dibromide monomers and dimers. A computational and electron diffraction study

The molecular structure of tin dibromide was investigated by high-level computational methods and gas-phase electron diffraction. The structural and vibrational characteristics of both SnBr 2 and Sn 2 Br 4 were determined by computations. To reach an agreement between computed and experimental bond lengths for SnBr 2 , very large bases and correlated methods are needed. For the dimer Sn 2 Br 4 , two low-energy geometries were found, one with C, and the other with C 2 v symmetry, the former with somewhat lower energy. Thermodynamic functions for gaseous SnBr 2 and Sn 2 Br 4 and their dimerization reaction have been calculated on the basis of the computed structures.