Assessing performance of diverse ONIOM methods in calculation of structures of organonickel and organopalladium compounds

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/LANL2MB 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 Å (bond length, Ni), 0.071 Å (bond length, Pd), 1.52° (bond angle, Ni), 1.43° (bond angle, Pd), 5.6° (dihedral angle, Ni), and 6.0° (dihedral angle, Pd), respectively. Its root mean squared errors for the whole systems were 0.096 Å (bond length, Ni), 0.088 Å (bond length, Pd), 2.18° (bond angle, Ni), 2.20° (bond angle, Pd), 11.0° (dihedral angle, Ni), and 11.5° (dihedral angle, Pd), respectively.