Vibrational behavior of calcium hydrogen triacetate monohydrate, CaH(CH3COO)3 • H2O

The IR and Raman spectra of calcium hydrogen triacetate monohydrate, CaH(CH3COO)(3) center dot H2O, (Speakman's classification: B type acid salt) in the 4000-400 cm(-1) frequency region are presented and discussed with respect to the fundamental vibrations of acetic acid species (CH3COO- and CH3COOH) and hydrogen bond vibrations due to both hydroxyl groups of CH3COOH and water molecules. The main spectral feature in the v(OH) stretching mode region is the appearance of two broad bands at about 2500 and 1950 cm(-1), designated as (AB) and C bands, respectively. The presence of ABC bands with their frequency positions and intensities as well as the (delta(OH) and gamma(OH) frequencies are spectroscopic evidence for strong asymmetrical hydrogen bonds between the acetic acid species. Their enthalpies of formation (Delta H) were calculated to be -48.4 and -52.7 U mol(-1). Frequencies of the uncoupled OD stretches of the crystallization water reveal that H2O(2) forms stronger hydrogen bonds than H2O(1) and that the non-coordinated acetate oxygen is a stronger hydrogen bond acceptor than the carbonyl oxygen. The IR and Raman spectra of Ca(CH3COO)(2). H2O are also presented and discussed.