The curve fitting procedure has been performed for both IR and Raman spectra in SO and CH stretching regions for lithium salts solutions in diethylsulfoxide (DESO). The broad S=O stretching bands of DESO (1100 - 950 cm"1) show seven or eight components on band deconvolution. On thè basis of thè previous studies [1, 2] on solution DESO in aqueous and non-aqueous solutions, thè various components are assigned to free and associated species of DESO. The low-frequency component observed in solutions of lithium chloride in DESO at 1007 cm"1 is assigned to cation-molecular complexes. Lf-DESO associate is formed through thè interaction between Li* and S=O group of DESO, that leads to thè increase of SO stretching frequency. The spectral changes of thè SO stretching bands indicate that interaction between thè Li* ion and diethylsulfoxide breaks partially down thè self-association of thè solvent. In both IR and Raman spectra thè curve fitting procedure in CH stretching region (3000-2700 cm"1) gives five components, caused by antisymmetric and symmetric stretching vibrations of CH3 and CH2 groups of DESO. It is observed that both CH3 and CH2 stretching bands are shifted to thè high-frequency side in solutions of lithium nitrate and perchlorate in DESO, and to low-frequency side in solutions of lithium chloride in com-parison with their position in pure DESO. The increase of thè salt concentration in thè solution not only results in thè formation of Li*-DESO associates, but also makes thè elec-tronic nebula of thè C-H bond increase by way of thè induction effect transferred along thè molecular chain. This mechanism can explain thè changes in thè frequency of thè CH stretching modes in case of lithium nitrate and perchlorate solutions. The low-frequency shift in solutions of lithium chloride indicates thè existence of interactions between thè CH2 group of DESO and thè chloride anion. The curve fitting procedure performed for thè out-of-plane bending of NO}" anion (840-820 cm"1) in IR spectra, and for thè totally symmetric stretching vibration of C1O4" anion (950-920 cm"1) in Raman spectra has shown thè coexistence of free ions and contaci ion pairs. The comparison of experimental and theoretical calculated frequencies shows that thè coordination of C1O4" in thè ion pairs Li*ClO4" is monodentate.
S.A. Markarian, L.S. Gabrielian, S. Bonora, A. Trinchero (2004). FTIR and Raman study of lithium salts solutions in diethylsulfoxyde.. KRAKOW : Akapit Publisher.
FTIR and Raman study of lithium salts solutions in diethylsulfoxyde.
BONORA, SERGIO;TRINCHERO, ANDREA
2004
Abstract
The curve fitting procedure has been performed for both IR and Raman spectra in SO and CH stretching regions for lithium salts solutions in diethylsulfoxide (DESO). The broad S=O stretching bands of DESO (1100 - 950 cm"1) show seven or eight components on band deconvolution. On thè basis of thè previous studies [1, 2] on solution DESO in aqueous and non-aqueous solutions, thè various components are assigned to free and associated species of DESO. The low-frequency component observed in solutions of lithium chloride in DESO at 1007 cm"1 is assigned to cation-molecular complexes. Lf-DESO associate is formed through thè interaction between Li* and S=O group of DESO, that leads to thè increase of SO stretching frequency. The spectral changes of thè SO stretching bands indicate that interaction between thè Li* ion and diethylsulfoxide breaks partially down thè self-association of thè solvent. In both IR and Raman spectra thè curve fitting procedure in CH stretching region (3000-2700 cm"1) gives five components, caused by antisymmetric and symmetric stretching vibrations of CH3 and CH2 groups of DESO. It is observed that both CH3 and CH2 stretching bands are shifted to thè high-frequency side in solutions of lithium nitrate and perchlorate in DESO, and to low-frequency side in solutions of lithium chloride in com-parison with their position in pure DESO. The increase of thè salt concentration in thè solution not only results in thè formation of Li*-DESO associates, but also makes thè elec-tronic nebula of thè C-H bond increase by way of thè induction effect transferred along thè molecular chain. This mechanism can explain thè changes in thè frequency of thè CH stretching modes in case of lithium nitrate and perchlorate solutions. The low-frequency shift in solutions of lithium chloride indicates thè existence of interactions between thè CH2 group of DESO and thè chloride anion. The curve fitting procedure performed for thè out-of-plane bending of NO}" anion (840-820 cm"1) in IR spectra, and for thè totally symmetric stretching vibration of C1O4" anion (950-920 cm"1) in Raman spectra has shown thè coexistence of free ions and contaci ion pairs. The comparison of experimental and theoretical calculated frequencies shows that thè coordination of C1O4" in thè ion pairs Li*ClO4" is monodentate.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
