Submillimeterwave spectrum of CH 2PH and equilibrium structures of CH 2PH and CH 2NH

Abstract

The rotational spectrum of phosphaethene (CH 2PH) was reinvestigated. One hundred and nineteen new lines were measured in the submillimeter range from 500 to 650 GHz. The determination of the centrifugal distortion constants is significantly improved. As the molecule is close to symmetric prolate top, both reduction A and S were compared. 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-zeta quality and a core correlation correction. The structure of CH 2PH was compared to that of CH 2NH which was also determined for this goal. It is found that the semi-experimental structure of CH 2NH is less accurate than the ab initio structure. It is also found that the methylene group is much more asymmetric in CH 2NH than in CH 2PH.