D. Chakraborty et S. Manogaran, GROUND-STATE VIBRATIONS OF GUANIDINIUM AND METHYLGUANIDINIUM IONS - AN AB-INITIO STUDY, Indian journal of chemistry. Sect. A: Inorganic, physical, theoretical & analytical, 33(11), 1994, pp. 969-977
The results of ab initio SCFMO calculations using 6-31G basis set for
guanidinium - d0,d6 and methylguanidinium - d0,d5 ions are presented.
The optimized geometries from these calculations have been compared w
ith experimental bond distances and bond angles obtained from crystal
structures. The vibrational spectra (frequencies and intensities) for
the compounds and their deuterated isotopomers have been calculated us
ing the same basis set. The predicted spectra have been compared with
the experimental IR and Raman spectra of the molecules and their isoto
pomers in solid state as well as in solution. The calculated potential
energy distribution provides a basis for assigning the experimental s
pectra. The isotopic frequency shifts for H-2 substituted guanidinium
ion and methylguanidinium ion are also found to be in close agreement
with the experimental isotopic frequency shift. The calculated IR inte
nsity pattern also shows good agreement with the experimental spectrum
.