A study of hydrogen bonded vibrational spectra of (R)-(+)-Methylsuccinic acid, as aided by DFT dimer analysis

作者：Tonannavar J^*; Chavan Yashaswita B; Yenagi Jayashree

来源：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy , 2016, 160: 19-25.

DOI：10.1016/j.saa.2016.02.011

• (R)-(+)-Methylsuccinic acid
• O-H center dot center dot center dot OC hydrogen bonding
• Density functional theory
• IR
• Raman

Infrared and Raman spectral measurements in the region 4000-400 cm(-1) have been carried out for (R)-(+)-Methylsuccinic acid. The vibrational band structures near 3100-3040 cm(-1) in the IR and near 1650 cm(-1) in the Raman spectra have indicated the presence of an inter-molecular hydrogen bonding. A DFT dimer model has been proposed that involves O-H center dot center dot center dot OC type of hydrogen bonding. The proposed dimer model has been derived from the three stable monomers computed at RHF/3-21G and B3LYP/6-311+G(d,p) levels of theory. A total of six dimer structures have been considered with a Boltzmann population of 38% for the most stable dimer and 62% for the remaining five dimer populations. A Boltzmann population weighted vibration spectrum has predicted bands, among others, for O-H center dot center dot center dot OC group that are in very good agreement with experiment. All the dimers have the same structure in that the two pairs of -O-H and -OC form a closed cyclic structure with a local center of inversion. This dimer geometry has given rise to one asymmetric mode at 1683 and one symmetric-CO mode at 1637 cm(-1) corresponding to mutually exclusive an experimental IR band at 1700 and a Raman band at 1651 cm(-1). Further, the bond length, H center dot center dot center dot O, for the most stable dimer is 1.686 angstrom, being shorter than the sums of van der Waals radii, 2.72 angstrom and the angle between O-H and H center dot center dot center dot O is almost linear (179 degrees) suggesting that the hydrogen bonding is fairly strong.

• 出版日期2016-5-5