Very low H-O-H bending frequencies. I. Overview and infrared spectra of NiKPO4 center dot H2O and its deuterated analogues

Very low H-O-H bending frequencies (appreciably lower than that in gaseous water) have been observed in the infrared spectra of several compounds of t he MKPO4.H2O type. Thus, in the case of NiKPO4.H2O the only intense band at tributable to the H-O-H bending appears at 1478 cm(-1), whereas in the case of the magnesium compound the corresponding frequency is 1470 cm(-1). A te ntative explanation (supported by quantum chemical calculations) for this u nusual phenomenon has been offered. (C) 2000 Elsevier Science B.V. All righ ts reserved.