Ligation state of nickel during C-O bond activation with monodentate phosphines
Hooker, Leidy V.
Neufeldt, Sharon R.
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The oxidative addition of phenolic electrophiles at Ni(0) in the presence of monodentate phosphine ligands was studied with both dispersion-free and dispersion-containing DFT methods. With the popular bulky ligand PCy3, consideration of dispersion has a striking effect on the predicted ligation state of nickel during oxidative addition of aryl sulfamates. Dispersion-containing methods such as M06L indicate a clear preference for a bis-phosphine ligated transition state (TS), while dispersion free methods like B3LYP strongly favor a mono-phosphine ligated TS. This discrepancy in predicted ligation state is also found with small phosphines (PMe3) in combination with some aryl electrophiles (carbamates, acetates, pivalates, chlorides), but a bis-PMe3-ligated TS is predicted regardless of dispersion for other electrophiles (sulfamates, mesylates, tosylates). DFT calculations that include dispersion also offer a possible explanation for the observed poor efficacy of PtBu3 as a ligand in Ni-catalyzed cross-coupling reactions.
Hooker, Leidy V., and Sharon R. Neufeldt. “Ligation State of Nickel During C O Bond Activation with Monodentate Phosphines.” Tetrahedron 74, no. 47 (November 2018): 6717–6725. doi:10.1016/j.tet.2018.10.025.