THEORETICAL-STUDY OF THE CU(H2O) AND CU(NH3) COMPLEXES AND THEIR PHOTOLYSIS PRODUCTS

Equilibrium geometries, binding energies, harmonic vibrational frequen cies, infrared intensities, and isotopic shifts have been calculated f or the Cu(H2O) and Cu(NH3) complexes and their photolysis products [HC uOH, CuOH, HCu(NH2), and Cu(NH2)] using Kohn-Sham theory with a gradie nt-corrected nonlocal potential. Cu(H2O) and Cu(NH3) are weakly bound systems, their binding energies are estimated to be 3.7 and 12.0 kcal/ mol, respectively. The HCuOH and HCu(NH2) insertion products are 2.4 a nd 6.3 kcal/mol less stable than Cu(H2O) and Cu(NH3), whereas H+CuOH a nd H+Cu(NH2) lie 49.7 and 58.0 kcal/mol above Cu(H2O) and Cu(NH3), res pectively. The calculated harmonic frequencies agree remarkably well w ith matrix-isolation infrared data; the agreement is always within 50 cm(-1) (30 cm(-1) on average) and the mean relative deviation from the experimental frequencies is 2.8%. The calculated isotopic frequency s hifts are in close agreement with experiment, except for normal modes, where two or more types of vibrations are coupled. For these modes, t he sum of the isotopic shifts is accurately reproduced. The sensitivit y of the calculated properties to the numerical integration grid has b een investigated and it is found that the grid usually used for main-g roup molecules has to be extended to obtain numerically stable vibrati onal properties for transition metal-ligand systems. (C) 1995 American Institute of Physics.