Microwave and high resolution infrared spectra of vinyl chloride, ab initio anharmonic force field and equilibrium structure

摘要

The quadratic, cubic, and semi-diagonal quartic force field of vinyl chloride has been calculated at the MP2 level of theory employing a basis set of triple-zeta quality. The spectroscopic constants derived from this force field are compared with the experimental values. To make this comparison more complete, the rotational constants of the lowest excited state, nu(9) = 1 at 395 cm(-1) have been determined by microwave spectroscopy and the nu(12) band (around 618 cm(-1)) has been investigated by high-resolution infrared Fourier transform spectroscopy. The equilibrium structure has been derived from experimental ground state rotational constants and ab initio rovibrational interaction parameters. This semi-experimental structure is in excellent agreement with the ab initio structure calculated at the CCSD(T) level of theory using a basis set of quintuple-C quality and a core correlation correction. The experimental mass-dependent r(m) structures are also determined and their accuracy is discussed. The recommended equilibrium geometry is: r(C=C) = 1.3262(10), r(C-CI) = 1.7263(10) r(C-H-g) = 1.0784(10), r(C-H-c) - 1.0795(10), r(C-H-t) = 1.0797(10), angle(CCCI) - 122.77(10)degrees, angle(CCHg) = 123.86(10)degrees, angle(CCHc) = 121.80(10)degrees, angle(CCHt) = 119.29(10)degrees. (c) 2005 Elsevier Inc. All rights reserved.