Hexafluorosilicates of alanine

Abstract

The existence of three types of salts of amino acid hexafluorosilicates 2 A+ · SiF62–, A2+ · SiF62– and 2(A ··· A+) · SiF62–, where A is an amino acid in zwitterionic state, A+ is a singly charged cation, A2+ is a doubly charged cation and (A ··· A+) is a dimeric cation with a short hydrogen bond, have been established, in the literature (Ghazaryan, V. V.; Fleck, M.; Petrosyan, A. M.: Salts of amino acids with hexafluorosilicate anion. J. Cryst. Growth (2011), doi: 10.1016/j.jcysgro.2011.11.017). Here we report the investigation of hexafluorosilicates of α-alanine. Both L- and DL-alanine form salts according to the main 2 A+ · SiF62– type: 2L-Ala+ · SiF62– · 3 H2O and 2DL-Ala+ · SiF62– · 2 H2O. In addition we found that L-alanine forms a new A+ · (A ··· A+) · SiF62– type of salt: L-Ala+ · (L-Ala ··· L-Ala+) · SiF62– · H2O. Results of structural and vibrational spectroscopic studies are described and discussed.