After the oxidative addition reaction and isomerization steps, the next logical transformation is the transmetalation step. In the present case, the transmetalation consists in the reaction between the intermediate obtained after the isomerization (F or 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 nickel atom whereas the other boron eliminates together with the fluorine ligand. This is what we call the classical transmetalation mechanism. However, as we mentioned above, the participation of the sodium phenolate is not clear and could modify this step precisely. For this reason, we considered three possibilities: (i) the classical transmetalation; (ii) a non-classical transmetalation,  with the participation of one molecule of the neutral base, NaOPh; and (iii) a non-classical transmetalation with the anionic phenoxide base for both bis- and mono-phosphine complexes.
All the results make to think us that after the isomerization path, the mono-phosphine trans intermediate (FM) reacts with the adduct G forming the pre-adduct GM which is more stable than the other pre-adducts (GPSPM and SM). Then, the trans-metalation goes through the TSGM→HM giving the HM post-adduct. This HM post-adduct decomposes giving the third intermediate IM and a sub-product J.  Therefore, the most favourable mechanism is a non-classical transmetalation,  with the participation of one molecule of the neutral base, NaOPh for mono-phosphine complexes.
Finally, we reach the last step of the mechanism. As for the cross-coupling mechanism, the last step is the reductive elimination reaction, in which the new C-B bond is formed and the catalyst recovered by the formal reduction of the metal atom. the reductive elimination through mono-phosphine compounds is more favorable than through bis-phosphine species.