The parent metallacyclobutane has the formula LM(CH) where L is a ligand attached to M. A stable example is (PPh)Pt(CH). The first example was prepared by oxidative addition of cyclopropane to platinum.
Metallacyclobutane intermediates are involved in the alkene metathesis and in the oligomerization and dimerization of ethylene. In alkene metathesis, the Chauvin mechanism invokes the attack of an alkene at an electrophilic metal carbene catalyst.  This work helped to validate the Chauvin mechanism for olefin metathesis.