Vibrational spectra and structure of N-methylacetamide in some solid complexes with neutral salts

Abstract

Infrared spectra of crystalline complexes of N-methylacetamide (CH3CONHCH3) and of its ND analog with alcaline perchlorates, tetrabutylammonium halogenides, and alcaline halogenides have been investigated in NH stretching (3500–3050 cm−1), CO stretching (amide I, 1750–1500 cm−1), and NH bending (800–400 cm−1) regions. Possible structures for the complexes are proposed and the non-planarity of the amide group is discussed.

Solvent Dependence of theN-Methylacetamide Structure and Force Field

“…Calculated anharmonic peaks of the amide A (∼3545 cm −1 ) and I (1730 cm −1 ) modes are accompanied by satellite bands from Fermi resonances. Although these cannot be unambiguously assigned to an experimental signal, the sensitivity of the amide I vibration to the resonances is in qualitative agreement with the H 2 -matrix (Figure ) and other ,,,, experiments, and seems to be a general property of the carbonyl group in amides…”

“…Strong anharmonic interactions are indicated by band splitting frequently observed in experimental Raman and IR spectra, ,,, as well as by computational models . A full-dimensional anharmonic computation significantly improved harmonic frequencies and provided estimates of the combination bands .…”

“…For example, many Raman bands of pure NMA split at −120 °C, seven instead of the two expected fundamental bands appear within 1500−1700 cm −1 , some bands even change position by up to 20 cm −1 upon cooling, etc . Possible nonplanarity of the amide bond in the ground state and its spectroscopic consequences have been discussed for a long time, but never proven. − Significant influence of hydration on electronic and vibrational NMA properties was predicted . Lastly, methyl group rotation barriers were determined from a gas phase experiment and rationalized by quantum computations .…”

Nanostructured Triblock Copolymers with Chemically Complementary Components and Their Ionic Conductivity

“…It was shown earlier [47] that due to existence of both the long amorphous chains of PAAm and IntraPC formation, TBC structure preserved an amorphous character also at a high length of PEO block (up to M n ~ 40 kDa). This fact and also well-known capability of PEO oxygen atoms [1,3] and PAAm amide groups [48] to connect different ions were dominant for a production of solidstate electrolytes based on pure TBC films and those doped by ionic components. The electrolyte for DSSCs was doped by the Red/Ox couple KI/I 2 , which is usually applied for a regeneration of the oxidized dye [6,10,13,14], unlike the electrolyte for SSLB, which was filled with lithium salt (LiPF 6 ).…”

Ft‐Ir study of the interaction between N, N,1,9‐tetramethylguanine and the Li+ Ion. Comparison with protonation

“…Protonation of nucleic bases and their complexation with metal ions has a profound influence on their structure and reactivity (1)(2)(3). The interaction between the Li' ion and carbonyl bases has been investigated by vibrational spectroscopy (4)(5)(6)(7)(8), ab initio calculations (8)(9)(10)(11)(12)(13)(14)(15)) and X-Ray diffraction (16). Despite their biological interest, very few experimental results for the interaction between the nucleic acid bases and the Li + ion are available in the literature.…”