The variations in hydrogen bonding in hexafluorosilicate salts of protonated methyl substituted pyridines and tetramethylethylenediamine

The synthesis and spectroscopic characterization of hexafluorosilicate salts with organic cations (R)2[SiF6] (where R = 2-picolinium (1), 2,6-lutidinium (2) and 2,4,6-collidinium (3)) and R[SiF6]·2H2O (where R = tetramethylethylenediammonium (4)) are reported. The salts were prepared by the reaction of methyl substituted pyridines or tetramethylethylenediamine with hydrogen fluoride solution and subsequent addition of silica. The crystal structures of 1, 2 and 4 have been determined by single-crystal X-ray diffraction analysis. The effect of hydrogen bonding on the elongation of the SiF bonds is discussed.