Vibrational properties and DFT calculations of formamidine-templated Co and Fe formates

Experimental Raman and IR spectra of [NH2-CH-NH2][M(HCOO)3] (M = Co, Fe), containing formamidinium cations [NH2-CH-NH2]+ (FMD+) were recorded at room temperature. In order to assign the vibrational modes corresponding to the FMD+ cation, the three-parameter hybrid B3LYP density functional method has been used with the 6-311G(2d,2p) basis to derive the vibrational wavenumbers (harmonic and anharmonic), infrared intensities and Raman scattering activities of formamidine molecule and FMD+ cation. The performed calculations revealed that protonation should affect most significantly the ν(CH), ρ(NH2), ω(NH2) and τ(NH2) modes, which are expected to shift towards higher wavenumbers after protonation.