The FT-IR spectra of protiated and partially deuterated analogues of two novel cesium saccharinates, Cs(C7H4NO3S)(C7H5NO3S)·H2O (1) and Cs(C7H4NO3S)·0.5H2O (2) are studied. The v(CO) and v(SO2) frequency values, along with the presence of v(NH) absorption in the spectrum of 1, represent inevitable evidence that this compound is an adduct of molecular saccharin. Earlier spectra-structural and structural correlations in metal saccharinates are employed in conjunction with the IR spectral and thermal data to make structural inferences about the compounds. The appearance of low-frequency v(NH) absorption continuum in the spectrum of 1 suggests certain degree of dynamical disorder of the proton within the asymmetric [N-H···N]- hydrogen bonds of saccharinato ion-molecule couples. In addition, one (Cs) or two (C2v) crystallographic types of essentially non-hydrogen bonded water molecules are situated in its lattice. Structural criteria for estimation of the proton position within the adduct dimmers, based solely on various descriptors of the degree of saccharinato sulfocarboximide ring distortion, are proposed. It is shown that in addition to the diversity of bonding modes expressed by its deprotonated form, saccharin can also be incorporated in solid-state structures as a molecule, even in a typically ionic salt.
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