Oxidative addition

In a standard oxidative addition, a bond X–Y is cleaved and both fragments become metal ligands, increasing formal metal oxidation state by two. A B–Br bond can give a metal–boryl bond and a bromide ligand without cleaving a borazine ring.

A metal-assisted pathway in which cleavage of a substrate C-H bond transfers H to an electrophilic ligand while new metal-carbon bonding forms. In directed Fischer-carbene insertion, it can precede carbon-carbon reductive elimination.