A variable-temperature 79Br nuclear quadrupole resonance and X-ray crystallographic investigation of dimethylammonium hexabromostannate(IV), [NH2Me2]2[SnBr6]

Abstract

A variable-temperature ⁷⁹Br n.q.r. Study of dimethylammonium hexabromostannate, [NH₂Me₂]₂[SnBr₆], in the range 77–300 K, has shown that a phase transition occurs at 253 ± 1 K. At room temperature the crystals of the compound are orthorhombic, with a= 14.88(1), b= 7.61(1), c= 7.60(1)Å, Z= 2, and space group Pnnm. The structure has been refined to R= 0.076 for 846 diffractometer-measured intensities for which I > 3σ(I). Two Sn–Br bonds in the anion are slightly longer [2.609(3)Å] than the remaining four [2.601(2)Å], in agreement with the n.q.r. results for the higher temperature phase. The results are interpreted in terms of stronger H-bonding in the low temperature phase.