Density Functional Theory Calculations on Ni—Ligand Bond Dissociation Enthalpies

Abstract

The formation and breaking of Ni—L (L=N-heterocyclic carbene, tertiary phosphine etc.) bond is involved in many Ni-catalyzed/mediated reactions. The accurate prediction of Ni—L bond dissociation enthalpies (BDEs) is potentially important to understand these Ni-complex involving reactions. We assess the accuracy of different DFT functionals (such as B3LYP, M06, MPWB1K, etc.) and different basis sets, including both effective core potentials for Ni and the all electron basis sets for all other atoms in predicting the Ni-L BDE values reported recently by Nolan et al. [J. Am. Chem. Soc. 125, 10490 (2003) and Organometallics 27, 3181 (2008)]. It is found that the MPWB1K/LanL2DZ:6-31+G(d,p)//MPWB1K/LanL2DZ:6-31G(d) method gives the best correlations with the experimental results. Meanwhile, the solvent effect calculations (with CPCM, PCM, and SMD models) indicate that both CPCM and PCM perform well.

Nickel N-Heterocyclic Carbene Catalysts for Ester Carbonylation

“…While NHC-based catalysts have now replaced many traditional phosphine-based catalysts (34)(35)(36)(37)(38), we are not aware of any studies of NHC-supported nickel catalysts for acetyl synthesis (39,40). Due to their strong electron donating nature, NHC ligands could have several advantages over phosphines: (a) stronger binding affinity to nickel and thus less loss of supporting ligands (41)(42)(43), (b) promotion of CO dissociation to generate active species (43,44), and (c) faster rates by acceleration of the MeI oxidative addition step (41,(43)(44)(45)(46), all while resisting methylation (47,48).…”