Knowledge Bank

The intermolecularly uncoupled fundamental frequencies of three isotopic species of water in various hydrogen-bonded systems have been determined from a study of the infrared spectra of several transition metal hydrates, those containing varying proportions of $H2O,D2O$ and HOD. The systems studied are the hydrates, $MnCl2CL22H2O,FeCl2CL22H2O,CoCl2Cl22H2O$ and $CuCl2Cl22H2O$. These frequencies, when used in a vibrational calculation, permitted the determination of the intramolecular stretch-stretch force constant, $Fiii$ for water in the condensed systems studied. This interaction constant was found to be more positive for water in hydrates than it is for water in the vapor. It was observed to increase with increasing hydrogen bonding. Possible origins of this increase are considered and its effect on the spectrum of liquid water explored.