Structure, vibrational assignment, normal coordinate analysis, and ab initio calculations of methylisocyanate

Theoretical, ab initio and DFT, study of the structure and vibrational analysis of Raman, IR and INS spectra of (CH3)3SiNCO

“…In general, the results agree for analogous force constants and the values of the N-C and C-O stretching force constants are in the range 13.7-15.0 mdyn Å À1 . Moreover, the values for N-C stretching in our work are somewhat longer than the value for C-O stretching force constant, which is in agreement with the values from the scaled quantum mechanical force field performed by Sullivan et al for methylisocyanate [54]. However, the values proposed for the N-C and C-O stretching force constants from the empirical force field when studying (CH 3 ) 3 SiNCO [17] and also similar compounds [56,57] are reversed, that is, N-C stretching being somewhat smaller than the values for C-O stretching force constants.…”

Structural and spectroscopic characterization of methyl isocyanate, methyl cyanate, methyl fulminate, and acetonitrile N-oxide using highly correlated ab initio methods

“…The band center positions were estimated combining both levels of theory. For MIC and MC, computed values are compared with the band center positions of the gas phase IR and Raman spectra measured by Sullivan et al 24 and the gas phase IR spectrum of Pasinszki and Westwood. 8 With few exceptions, there is an agreement between computed and observed band centers.…”

“…MIC structure was confirmed in a subsequent electron diffraction study by Anderson et al 22 Fateley and Miller observed far infrared transitions in gas phase. 23 The infrared and Raman spectra of the gas and solid phases were measured by Sullivan et al 24 in the 3200-20 cm −1 and 3200-10 cm −1 regions, respectively. Reva et al 25 recorded the infrared spectra of methyl isocyanate isolated in Ar, Xe, and N 2 matrices.…”

Photochemical Ring-Opening Reaction in 2(1H)-Pyrimidinones: A Matrix Isolation Study

“…Furthermore, detection of photoproduced species with isocyanate groups should be easy in a matrix isolation experiment combined with FTIR spectroscopy: the isocyanate moiety should manifest itself by a very intense infrared absorption band appearing within the characteristic frequency range 2280-2260 cm -1 . Intense bands lying within this frequency range were observed in the infrared spectra of simple, stable isocyanates: methylisocyanate 28 and ethylisocyanate. 29 However, to the best of our knowledge, conjugated isocyanates produced in an R-cleavage photoreaction have never been directly observed so far.…”