摘要

The performances of different ONIOM methods in the geometry optimizations of bulky organonickel and organopalladium compounds were systematically assessed for the first time. The whole system was always treated with the HF/LANIL2MB method while seven popular density functionals (B3LYP, PBEP86, B3P86, B3PW91, BPBE, PW91PW91, and BP86) and six popular ECP basis sets (CEP-121G, CRENBL, LANL2DZ, LANL2DZ + p, SDD, and sbkjcvdz) were examined for the core layer. It was concluded that the best method for the geometry optimizations was ONIOM(B3P86/LANL2DZ+p//HF/LANL2MB). Its average errors for the calculations of the whole systems were 0.076 angstrom (bond length, Ni), 0.071 angstrom (bond length, Pd), 1.52 degrees (bond angle, Ni), 1.43 degrees (bond angle, Pd), 5.6 degrees (dihedral angle, Ni), and 6.0 degrees (dihedral angle, Pd), respectively. Its root mean squared errors for the whole systems were 0.096 angstrom (bond length, Ni), 0.088 angstrom (bond length, Pd), 2.18 degrees (bond angle, Ni), 2.20 degrees (bond angle, Pd), 11.0 degrees (dihedral angle, Ni), and 11.5 degrees (dihedral angle, Pd), respectively.