Addition: Organometallic
Organometallic species M-R, where M is the metal and R an organic function, can add to alkene and other pi-bond systems.

The first step of this process involves vacant d-orbitals of the (Heavy Metal Lewis acid) metal centre complexing with the organic pi-system.

Organometallic chemists are inclined to consider this process as the insertion of the pi-bonded organic moiety into M-R.

For more information look in the Chemogenesis webbook sections on insertion reactions, addition reactions and the Lewis acid/base interaction matrix.