Density functional calculations on structures and Ni-CO bond dissociation energies of Ni (CO)(n)(n=1-4)

Density functional theory(DFT) methods with several functionals were used to determine geometries and harmonic frequencies of Ni(CO)_(n)(n=1—4) complexes.In consideration of the zero point energy(ZPE) and basis set superposition error(BSSE) corrections,the nickel carbonyl bond dissociation energies of these complexes have been evaluated.The obtained results show that hybrid DFT methods,such as B3LYP,yield reasonable geometries and vibrational frequencies.For Ni(CO)_(n)(n=2—4),the bond dissociation energies predicted by "pure" DFT methods,such as BP86 and BPW91,are in good agreement with those from the sophisticated coupled-cluster method,CCSD(T),and the experimental measurements.It was shown that the validity of the calculated bond dissociation energies for NiCO complex or the cumulative binding energies for other complexes strongly depends on an adequate description of BSSE.The calculated BSSE corrections are reasonable only if the electronic structures of the metal with and without ghost basis sets on the ligand positions are identical with that of the metal in metal complexes.The reasonable BSSE correction is the precondition for obtaining valid bond dissociation energies.