Infrared spectroscopy for formamide (FA) solutions of Ca(ClO4)2 shows that both CN stretch (νCN) and CO stretch (νCO) bands of FA undergo upshifts in the presence of Ca2+. Modeling of Ca2+ in FA solutions is accomplished by quantum chemical calculations for Ca2+(FA)n (n = 1–8) complexes with Polarizable Continuum Model (PCM). The calculations indicate that bidentate Ca2+(FA)4 complexes are not consistent with the observed upshift of the νCN band, although a bidentate coordination of four FA molecules via both O and N atoms was assumed in a previous study of the same system. The experimental results are reasonably reproduced by adopting Ca2+(FA)7 and Ca2+(FA)8 complexes with a monodentate coordination of all FA molecules via the O atom. A strong coupling among the CO oscillators is shown to be responsible for the upshifts of the νCO modes despite the O atom coordination.
|Number of pages||8|
|Journal||Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy|
|Publication status||Published - Jan 5 2019|
All Science Journal Classification (ASJC) codes
- Analytical Chemistry
- Atomic and Molecular Physics, and Optics