Molecular structure and infrared spectra of guanidinium cation: A combined theoretical and spectroscopic study

The guanidinium cations seem to be very interesting chemical species which can be used in design of molecular complexes with exactly planed chemical and physical properties suitable for nonlinear optics (NLO).The molecular structure of guanidinium cation C(NH₂)⁺ has been calculated with the aim of density functional (B3LYP) method with the extended 6-311 + G(df,dp) basis set. The calculated geometrical parameters of guanidinium cation in gas phase were compared with experimental data of other guanidinium compounds. The harmonic frequencies and IR and Raman intensities of C(NH₂)⁺ were calculated with the B3LYP method using 6-311 + G(df,dp) basis set. The calculated frequencies were compared with the experimental ones observed in vibrational spectra measured for three newly obtained compounds in which guanidinium cation is common component. The assignment of the experimental spectra has been made on the basis of the calculated potential energy distribution (PED).