The Organometallic HyperTextBook Alkene Complexes General Information Alkene or olefin ligands are common in organotransition metal chemistry. An alternative way of stating this would be to say that the hybridization of the alkene carbon changes from sp 2 to sp 3 as back-donation increases.
Electronic factors play a large role in the binding of alkenes to transition metals.
The stability of alkene complexes also depends on steric factors as well. Reduction of a higher valent metal in the presence of an alkene. The bonding of an alkene to a transition metal can activate the ligand to electrophilic or nucleophilic attack depending on the nature and charge of the metal center. Likewise, electron rich metal centers in low oxidation states are activated for attack by electrophiles at the C-C bond. The reaction chemistry of these complexes is quite broad and could form another textbook in itself.