Rotational spectrum and structure of HCP

The ground state rotational spectra of HCP, (HCP)-C-13, DCP, and (DCP)-C-13 have been measured in the millimeter-wave and submillimeter-wave ranges. For HCP and DCP, the rotational spectra in the vibrationally excited states v(2) = 1, 2 and v(3) = 1 have also been analyzed. The equilibrium structure has been calculated ab initio and experimentally redetermined. The derived structure is compared to those of the similar molecules FCP and ClCP and its accuracy is discussed. The equilibrium structure of FCP has also been redetermined by combining the experimental rotational constants and ab initio calculations. (C) 1996 Academic Press, Inc.