The structure and the internal dynamics of the lactam 1,3-dimethyl-2-imidazolidinone, also known as N,Nâ²-dimethylethyleneurea, have been investigated through the analysis of its free-jet absorption rotational spectrum. One conformer has been assigned. The pure μb-type spectrum, recorded in the 59.6â74.4 GHz frequency range entails an inertial defect Îc= â16.39 uà 2, indicating that the molecule has C2symmetry with a twisted arrangement of the ring. The methyl internal rotation barrier V3= 7.181 (3) kJ molâ1and the14N diagonal nuclear quadrupole coupling constants Ïaa= 2.14 (14) and (Ïbb-Ïcc) = 7.26 (6) MHz were determined from the analysis of the hyperfine structure. They are in good agreement with the ab initio MP2/6-311++G(d,p) calculations which also estimate the electric dipole moment value as 3.9 D.
Vigorito, A., Paoloni, L., Calabrese, C., Evangelisti, L., Favero, L.B., Melandri, S., et al. (2017). Structure and dynamics of cyclic amides: The rotational spectrum of 1,3-dimethyl-2-imidazolidinone. JOURNAL OF MOLECULAR SPECTROSCOPY, 342, 38-44 [10.1016/j.jms.2017.04.014].
Structure and dynamics of cyclic amides: The rotational spectrum of 1,3-dimethyl-2-imidazolidinone
Vigorito, Annalisa;Calabrese, Camilla;Evangelisti, Luca;Melandri, Sonia;Maris, Assimo
2017
Abstract
The structure and the internal dynamics of the lactam 1,3-dimethyl-2-imidazolidinone, also known as N,Nâ²-dimethylethyleneurea, have been investigated through the analysis of its free-jet absorption rotational spectrum. One conformer has been assigned. The pure μb-type spectrum, recorded in the 59.6â74.4 GHz frequency range entails an inertial defect Îc= â16.39 uà 2, indicating that the molecule has C2symmetry with a twisted arrangement of the ring. The methyl internal rotation barrier V3= 7.181 (3) kJ molâ1and the14N diagonal nuclear quadrupole coupling constants Ïaa= 2.14 (14) and (Ïbb-Ïcc) = 7.26 (6) MHz were determined from the analysis of the hyperfine structure. They are in good agreement with the ab initio MP2/6-311++G(d,p) calculations which also estimate the electric dipole moment value as 3.9 D.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.