Mossbauer spectra of tin(IV) iodide complexes

The first examples of compounds containing the [SnR2I3](-) anion, i.e. [(Bu 4N)-N-n][SnR2I3] (R=Me or Ph), have been prepared and characterized by IR, Raman and Sn-119 Mossbauer spectroscopies, and X-ray powder diffraction dat a. The experimental data are consistent with a trigonal bipyramidal structu re, with the R groups in equatorial positions, for the [SnR2I3](-) anions. Octahedral [SnR2I4](2-) anions could not be isolated and it is shown that t he previously reported [(Bu4N)-N-n](2)[SnMe2I4] is actually a 1:1 mixture o f (Bu4NI)-N-n and [(Bu4N)-N-n][SnMe2I3]. The X-ray powder structure of Cs2S nI6 has been refined by the Rietveld method. The compound crystallises in t he cubic Fm3m space group with a =11.6410(3) Angstrom and a Sn-I distance o f 2.864(1) Angstrom. The Sn-I distances in Cs2SnI6, SnI4(bipy), SnI4(Ph3PO) (2) and SnI4(Ph2SO)(2) are related to the Mossbauer quadrupole splitting, s howing that ligands that are weaker donors than I- (i.e. have a more positi ve partial quadrupole splitting) give rise to Sn-I distances that are short er than for the [SnI6](2-) anion.