VIBRATIONAL FREQUENCIES AND INTRAMOLECULAR FORCES IN ANIONIC TIN-HALOGEN COMPLEXES AND RELATED SPECIES

Far-infrared and Raman spectra are reported for solids containing the SnX62- (X = Cl, Br, I) and SnX3- (X = F, Cl, Br, I) ions in combination with large monopositive cations. These results include the first complete report of infrared- and Raman-active fundamentals for SnF3-, SnI3-, and SnI62-. Normal-coordinate vibrational analysis was performed for these complexes and for SnX4 (X = Cl, Br, I) under a uniform set of approximations. For a series of compounds containing the same halide it is found that the primary stretching force constants are approximately proportional to the metal oxidation state divided by the coordination number. Theoretical values for the force constants were calculated using an ionic model. These reproduce the reduction in force constant which is observed upon going from SnX4 to SnX62-. © 1969, American Chemical Society. All rights reserved.