Theoretical Study of Oxidative Additions of H2 and MeCN to a Nickel(0) Complex: Significantly Large Correlation Effects and Characteristic Features of the Reaction

• DOI: 10.1021/jp071816q
• Publication Date: 2007-07-17T11:00:30Z
• Authors: Yu-ya Ohnishi; Yoshihide Nakao; Hirofumi Sato; Shigeyoshi Sakaki
• Keywords: Transition state; Diatomic molecule

Oxidative addition of H2 to Ni(PH3)2 was theoretically studied as a prototype nickel-catalyzed sigma-bond activation reaction, where CASSCF, CASPT2, CCSD(T), broken symmetry (Bs) MP2 MP4(SDTQ), and DFT methods were employed. The CASPT2 method yields reliable potential energy curve (PEC) when the active space consists 10 electrons orbitals including five outer 3d' orbitals. CCSD(T) presents almost same PEC CASPT2-calculated one, either ANO or cc-pVTZ basis set is used for Ni. Bs-MP4(SDTQ)-calculated similar those calculated by CASPT2/ANO method, while not smooth around transition state. In calculation, ANO, cc-pVTZ, triple-zeta quality sets (SDB) with Stuttgart-Dresden-Bonn effective core potentials (ECPs) must be DFT-calculated reaction somewhat smaller than CASPT2- CCSD(T)-calculated values, B3PW91 mPW1PW91 present moderately better changes BLYP, B1LYP, B3LYP. MeCN investigated DFT(B3PW91) methods. Almost barrier these methods, employed However, underestimates binding reactant complex compared method. This oxidative exhibits interesting characteristic features, follows: height relative infinite separation lower, product more stable C2H6. These differences are discussed in detail terms Ni-Me Ni-CN bond energies participation CN pi* orbital stabilization interaction