Rotational Spectrum, Hyperfine Structure, and Internal Rotation of Methyl Carbamate

Equilibrium vs Ground-State Planarity of the CONH Linkage

“…All geometry optimizations indicate that in MC the amide group is slightly nonplanar at equilibrium. This is in apparent contrast to results of MW investigations, 8,9 measurement of the vibrationally averaged dipole moment of MC clearly shows that the molecule has a plane of symmetry, as µ c is zero. Fogarasi and Szalay 3 have demonstrated that MP2 optimizations wrongly predict a nonplanar structure for formamide, but in their work, the Hartree-Fock (HF) calculations predicted a planar structure.…”

“…Finally, it is noted that a fit of the available experimental data set 8,9 to an internal rotation Hamiltonian with a fixed value of V 6 of -20.3 cm -1 and V 9 of +1.6 cm -1 gave about the same standard deviation as the fit with V 6 ) V 9 ) 0 and the experimentally determined values of V 3 in the two cases differed by only 4%, a result which is expected when dealing with experimental data from the ground torsional state V t ) 0.…”

“…This observation received confirmation by electronic structure computations. 9 Components of the dipole moment vector of MC were determined experimentally by the Stark effect. 8 Accurate values of the 14 N quadrupole coupling constants and of the centrifugal distortion constants were determined by Fourier transform microwave (MWFT) and millimeterwave (MMW) spectroscopies, respectively.…”

The enthalpies of formation of alkyl carbamates: Experimental and computational redetermination

“…Methyl carbamate, an isomer of glycine, is a molecule with astrophysical interest, being a possible candidate for interstellar detection [19,20]. Moreover, it is used by the textile industry to the manufacture of resins, which are applied on polyester/cotton blend fabrics as durable-press finishes and as insecticides [21].…”

Quantum-chemical calculations of the structure, vibrational spectra, and torsional and inversion potentials of methylcarbamate

“…These were assigned to transitions between the ground and three low-lying excited inversion states, thereby confirming the hypothesis about the existence of two equivalent equilibrium positions of the amide hydrogens relative to the NC(O)OC plane. However, the lack of a c-component of the dipole-moment vector that was reliably established from an analysis of high-resolution microwave torsion-rotational spectra [15,16] was a very substantial argument in favor of planar NH 2 . The principal inversion state is located above a rather low potential barrier.…”