A THEORETICAL-STUDY OF THE MIGRATION OF HYDROGEN IN MOLECULE C2H AND MOLECULAR ION C2H-

The migration of hydrogen in C2H. and C2H-, and their stable minima in C2v symmetry are investigated using ab initio molecular orbital theor y at the HF/6-31 + G, CI and MCSCF level. For the C2H- ion, the hydro gen-migration experiences two equivalent transition states 1A' (C(s)) and a metastable state 1A1 (C2v). One transition state B-2(2) (C2v) is experienced for C2H.. The activation energies and rate constants for the migration reactions are estimated. For C2H., an electronic state 2 A1 (C2v) lower in energy at the MCSCF level than the transition state B-2(2) (C2v) is found to be a stable minimum on the Hartree-Fock poten tial energy surface.