AB-INITIO STUDIES ON D(8)MCL(PH3)(2)(C2H2), M=RH AND IR, COMPLEXES

The geometries and energies of the isomers in alkyne complexes MCl(PH3 )(2)(eta(2)-C2H2), M=Rh and Ir, are theoretically investigated using a b initio methods at the Hartree-Fock and up to MP4 level of theory and relativistic effective core potentials for Rh and Ir metals. The opti mized structures of Rh complexes, 1-3 at MP2/ECP1 level are in good ag reement with the related experimental data. The binding energies of C2 H2 to d(8)-metal fragments are computed to be similar to 55 kcal/mol. The vinylidene complexes for Rh and Zr metals are calculated to be muc h lower in energy than the alkyne complexes. The alkyne-vinylidene rea rrangement is possible to proceed exothermically through the intermedi ate hydrido-alkynyl complexes, 2 or 9. Detailed comparison is given ab out the geometries and relative energies on Rh and Zr isomers at the v arious level ab initio calculations with orbital analysis.