Conformational and structural determination of F(2)NC(O)F and F(2)NC(O)NCO. A joint experimental and theoretical study.
The vibrational properties of two difluoroaminocarbonyl species were analyzed by recording the FTIR spectra of the vapor for difluoroaminocarbonyl fluoride, F(2)NC(O)F, and difluoroaminocarbonyl isocyanate, F(2)NC(O)NCO. Moreover, the Raman spectrum of liquid F(2)NC(O)NCO was obtained. Vibrational assignments were made on the basis of a normal coordinate analysis and the evaluation of the band contours appearing in the FTIR spectrum of the vapor. The conformational space of both difluoroaminocarbonyl derivatives were studied by using the B3LYP and MP2 level of theory with extended basis sets [6-311+G(3df) and aug-cc-pVTZ]. Only one conformation belonging to the C(1) symmetry point group is expected for F(2)NC(O)F, whereas the overall evaluation of experimental and theoretical results suggests the existence of a mixture of two conformers for F(2)NC(O)NCO at room temperature. Its relative abundance of the most stable syn form (C=O double bond syn with respect to the N=C=O group) was estimated to be 56(5) %.
Erben
Mauricio F
MF
CEQUINOR (UNLP-CONICET, CCT La Plata), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC 962, La Plata (CP 1900), República Argentina.
Padró
Juan M
JM
Willner
Helge
H
Della Védova
Carlos O
CO