Homocoupling organometallic compounds

The last class of organometallic compounds that undergo Pd-catalyzed homocouphng are organomercury compounds. An early example of homocoupling of ahcenyhnercury... 

Homocoupling can involve either two organic halides (or their equivalent) or two organometallic compounds (Scheme 2.131). Palladium is often employed for this transformation. Neither reaction is of itself catalytic, but each can be rendered catalytic by the inclusion of either a reducing agent or an oxidizing agent. 

A number of organometallic compounds are suitable for the Pd-catalyzed homocoupling reaction. The homocoupling of group IV (Si, Sn, Pb) derivatives has been studied most extensively and developed into synthetically useful protocols. Also, derivatives of group III (B) and transition metals (Hg) have occasionally been used to obtain homocoupling products. 

---