Raman spectrum of the [SnI 3 ] − ion and other halogenostannate(II) complexes including mixed halides

The complete Raman spectrum of the pyramidal triiodostannate(II) ion [SnI 3 ] − (ν 1 = 162 cm − , strong, polarized; ν 2 = 61 cm − , medium, polarized; ν 3 = 148 cm − , strong, depolarized; ν 4 = 48 cm − , strong, depolarized) is observed in a diethyl ether extract from a solution of tin(II) iodide containing hydriodic acid. Previous reports of the frequencies of [SnCl 3 ] − are confirmed but for [SnBr 3 ] − ν 1 is revised from 211 to 205 cm −1 . The complex acids H[SnX 2 Y] and H[SnXYZ] (X, Y or Z = Cl, Br or I) are observed in solvent extracts of tin(II) mixed halide solutions and a set of ν(Sn—halogen) frequencies is compiled. Appreciable co‐extraction of [SnX 2 (H 2 O)] occurs at halogen acid concentrations below 3 mol l −1 .