After forming the catalyst Ni(PMe3)2 (B) from the precursor Ni(COD)2 (X)and PMe3 (Z), the oxidative addition takes place leading to E. The next step is the isomerization of intermediate E obtained in the oxidative addition reaction step. The square-planar complex E experiments a cis/trans isomerization process regarding the mutual disposition of the two phosphine ligands. This step is energetically less costly in monophosphine complexes EM and FM. Note that species E could not accommodate the diboron reagent because steric congestion.
The next step is the transmetalation. In the present case, the transmetalation consists in the reaction between the intermediate obtained after the isomerization FM and the diboron (C). In this step, both the Ni-F bond and the diboron B-B bond break, the boryl boron moiety will end coordinated to the metal centre, and the other boron moiety is eliminated together with the fluorine ligand. The participation of one molecule of the neutral base, NaOPh, provided the most favourable reaction pathway. Therefore, the mono-phosphine trans intermediate (FM) reacts with the adduct G forming the pre-adduct GM . Then, the transmetalation goes through the TSGM→HM giving the HM post-adduct. This HM post-adduct reacts with phosphine Z giving the third intermediate I and a sub-product J. Therefore, the most favourable mechanism is a non-classical transmetalation, with the participation of one molecule of the base in neutral form NaOPh.
Finally, we reach the last step of the reaction mechanism, in which the new C-B bond is formed and the catalyst recovered by formal reduction of the metal atom. I undergoes the reductive elimination and releases the product.