title: Isomerism of Cyanomethanimine: Accurate Structural, Energetic, and Spectroscopic Characterization.
abstract: The structures, relative stabilities, and rotational and vibrational parameters of the Z-C-, E-C-, and N-cyanomethanimine isomers have been evaluated using state-of-the-art quantum-chemical approaches. Equilibrium geometries have been calculated by means of a composite scheme based on coupled-cluster calculations that accounts for the extrapolation to the complete basis set limit and core-correlation effects. The latter approach is proved to provide molecular structures with an accuracy of 0.001-0.002 Å and 0.05-0.1° for bond lengths and angles, respectively. Systematically extrapolated ab initio energies, accounting for electron correlation through coupled-cluster theory, including up to single, double, triple, and quadruple excitations, and corrected for core-electron correlation and anharmonic zero-point vibrational energy, have been used to accurately determine relative energies and the Z-E isomerization barrier with an accuracy of about 1 kJ/mol. Vibrational and rotational spectroscopic parameters have been investigated by means of hybrid schemes that allow us to obtain rotational constants accurate to about a few megahertz and vibrational frequencies with a mean absolute error of ∼1%. Where available, for all properties considered, a very good agreement with experimental data has been observed.
authors.affiliation: Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna , Via Selmi 2, I-40126 Bologna, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Puzzarini
mesh_terms: D000607:Aminoacetonitrile / Q000737:chemistry*; D003198:Computer Simulation; D007536:Isomerism; D008956:Models, Chemical; D015394:Molecular Structure; D011789:Quantum Theory; D012399:Rotation; D013057:Spectrum Analysis; D014732:Vibration
chemical_list: D000607:Aminoacetonitrile