Millimeter-wave spectroscopy of HC3P isotopomers and coupled-cluster calculations: the molecular structure of phosphabutadiyne

The rotational spectrum of the unstable HC3P molecule has been investigated in the millimeter-wave region. Five different isotopomers were studied, in cluding also the three C-13-containing species which were detected in natur al abundance. The obtained ground state rotational constants allowed us to evaluate the r(0) and r(s) molecular structures of phosphabutadiyne. CCSD(T ) calculations were performed using the cc-pVQZ basis, and theoretically co mputed vibration-rotation coupling constants were combined with experimenta l ground state rotational constants to determine an accurate equilibrium st ructure. (C) 2000 Published by Elsevier Science B.V. All rights reserved.