Infrared Studies of Water in Crystalline Hydrates: Location of Hydrogen Atoms and Evidence for a Bifurcated Hydrogen Bond in K2SnCl4•H2O

Abstract

Infrared spectra of polycrystalline K2SnCl4•H2O at different degrees of deuteration were recorded between 4000 and 300 cm−1 at temperatures between 30 and −160 °C. The spectra are consistent with the crystal structure proposed by Kamenar and Grdenić. The water molecules are all equivalent and asymmetric. They are sufficiently well separated from one another for the dynamic coupling of vibrations to be negligible. Both hydrogens of the water molecule participate in hydrogen bonding; one of the hydrogen bonds is weak and bifurcated. Positional parameters of the hydrogen atoms have been calculated using supplementary information from available n.m.r. studies. Infrared spectral characteristics of water molecules engaged in bifurcated hydrogen bonding are discussed.