The structure and the internal dynamics of the lactam 1,3-dimethyl-2-imidazolidinone, also known as N,N'-dimethylethyleneurea, have been investigated through the analysis of its free-jet absorption rotational spectrum. One conformer has been assigned. The pure ?b-type spectrum, recorded in the 59.6-74.4 GHz frequency range entails an inertial defect Delta(c) = -16.39 uÅ2, indicating that the molecule has C2 symmetry with a twisted arrangement of the ring. The methyl internal rotation barrier V3 = 7.181 (3) kJ mol-1 and the 14N diagonal nuclear quadrupole coupling constants Xaa = 2.14 (14) and (Xbb-Xcc) = 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.
Structure and dynamics of cyclic amides: The rotational spectrum of 1,3-dimethyl-2-imidazolidinone
Favero;
2017
Abstract
The structure and the internal dynamics of the lactam 1,3-dimethyl-2-imidazolidinone, also known as N,N'-dimethylethyleneurea, have been investigated through the analysis of its free-jet absorption rotational spectrum. One conformer has been assigned. The pure ?b-type spectrum, recorded in the 59.6-74.4 GHz frequency range entails an inertial defect Delta(c) = -16.39 uÅ2, indicating that the molecule has C2 symmetry with a twisted arrangement of the ring. The methyl internal rotation barrier V3 = 7.181 (3) kJ mol-1 and the 14N diagonal nuclear quadrupole coupling constants Xaa = 2.14 (14) and (Xbb-Xcc) = 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.
