THEORETICAL-STUDY OF THE C3P RADICAL AND ITS CATION

An ab initio molecular orbital study has been carried out for the C3P radical and its positive ion, C3P+. Geometries, vibrational frequencie s, and infrared intensities have been obtained at the MP2/6-31G level , whereas MP4 theory has been employed to compute electronic energies. A topological analysis of the electron density for nonlinear species has also been carried out. The neutral species is predicted to have a linear ground state (2 Pi electronic state), the next lowest-lying iso mer (about 15 kcal/mol higher in energy) being a rhomboidal species wi th B-2(1) electronic state. Both isomers have high dipole moments, 2.7 73 and 3.893 D, respectively, which should favor their experimental de tection. In the case of the cation the ground state is also predicted to be a linear structure ((3) Sigma(-) electronic state). The next low -lying isomer is a triplet rhomboidal structure which lies about 10 kc al/mol higher than the C3P+ ground state at correlated levels. Therefo re, it seems that, Like their sulfur analogues and contrary to the sil icon compounds, the CnP species have linear ground states.