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To explore how the ion-pair in a single salt molecule evolves with the addition of water, infrared (IR) spectra of complexes composed of NaCl and multiple water molecules have been recorded for the first time. The NaCl(H2O)n complexes were formed and probed in liquid helium nanodroplets, and IR spectra were recorded for n = 1 → 4. The spectra for n = 1, 2, and 3 are consistent with formation of the lowest energy contact-ion pair structures in which each water molecule forms a single ionic hydrogen bond to an intact Na+Cl- ion-pair. Alternative structures with hydrogen bonding between water molecules become energetically competitive for n = 4, and the IR spectrum indicates likely the coexistence of at least two isomers. [ABSTRACT FROM AUTHOR]

The Infrared (IR) spectroscopy of alkali earth halide salt (MX2) complexes with few numbers of water molecules have been investigated for the first time in this work. BeCl2 and MgCl2 are divalent salts and have been incorporated with water as a polar solvent to form complexes of type MX2(H2O)n. The effect of ion size plays a critical rule in the interactions between solvent and solute. Therefore, Beryllium and Magnesium salts with chloride were chosen to explore this difference. The importance of BeCl2 and MgCl2 comes from their several applications in the industry and pharmacy. For instance, BeCl2 is widely used in the industry as a catalysis of Friede-Craft reactions, while the main application of MgCl2 in pharmacy is as hemodialysis and peritoneal dialysis fluids. Three complexes of each BeCl2 and MgCl2 with water, MX2(H2O)n (n=1-3), were studied, and the chemical structures of these complexes have been performed using ab initio calculations. Ab initio calculations were used to predict possible structures, isomers, and their corresponding IR spectra using Second-order Møller-Plesset perturbation theory (MP2) with 6-311++G as a basis sets. The Geometry evaluations, energy searches, vibrational frequency calculations, and the binding energy of each complex were also extracted theoretically. The minimum energy of complexes structures was calculated, and different isomers have been recorded. Ionic hydrogen bonds (IHBs) between the OH in each water molecule and the chloride ion in the MCl2 was proposed to be the main prevalent contribution to the binding between the salt and water. The bond length between the alkaline metal and chlorine showed a significant increase with increasing the attached water molecule as a result of forming the IHB. Also, the infrared vibrational bands of the OH stretching region were recorded for the minimum structures, and dramatic redshift was performed. The formation of contact-ion pair structures in which each solvent molecule forms an ionic hydrogen bond (IHB) to the salt ion-pair (X-M+X-) has been confirmed by the predicted infrared spectra. [ABSTRACT FROM AUTHOR]

Infrared (IR) spectra of complexes between NaCl and methanol have been recorded for the first time. These complexes were formed in liquid helium nanodroplets by consecutive pick-up of NaCl and CH3OH molecules. For the smallest NaCl(CH3OH)n, complexes where n = 1-3, the IR data suggest that the lowest-energy isomer is the primary product in each case. The predominant contribution to the binding comes from ionic hydrogen bonds between the OH in each methanol molecule and the chloride ion in the NaCl, as established by the large red shift of the OH stretching bands compared with the isolated CH3OH molecule. For n ≥ 4, there is a dramatic shift from discrete vibrational bands to very broad absorption envelopes, suggesting a profound change in the structural landscape and, in particular, access to multiple low-energy isomers. [ABSTRACT FROM AUTHOR]

Infrared (IR) spectra of complexes between NaCl and methanol have been recorded for the first time. These complexes were formed in liquid helium nanodroplets by consecutive pick-up of NaCl and CH 3 OH molecules. For the smallest NaCl(CH 3 OH) n , complexes where n = 1-3, the IR data suggest that the lowest-energy isomer is the primary product in each case. The predominant contribution to the binding comes from ionic hydrogen bonds between the OH in each methanol molecule and the chloride ion in the NaCl, as established by the large red shift of the OH stretching bands compared with the isolated CH 3 OH molecule. For n ≥ 4, there is a dramatic shift from discrete vibrational bands to very broad absorption envelopes, suggesting a profound change in the structural landscape and, in particular, access to multiple low-energy isomers.