Our ability to selectively activate and functionalize C-H bonds in organic molecules is fundamental to countless chemical processes. Despite notable advances in this field, strategies for the selective functionalization of sp C-H bonds of alkenes are underdeveloped. This limitation can be traced back to fundamental selectivity issues that emerge on reaction of alkenes with single-site transition metal complexes. π-Coordination of the alkene to the metal is often kinetically accessible and nonreversible (Figure ). The dominance of this pathway can effectively inhibit available mechanisms for vinylic C-H activation, including oxidative addition. The selectivity contrasts the rich chemistry of aromatic sp 2 C-H or aliphatic sp C-H bonds where substrate binding (π-coordination or σ-complex formation) is typically reversible and a pre-requisite for C-H bond breaking by oxidative addition. For example, Bergman and coworkers have studied the reaction of ethylene with the 16-electron reaction intermediate [IrCp*(PMe)3]. They found that π-complexation of the alkene is thermodynamically favored with respect to oxidative addition of vinylic sp C-H bonds. Moreover, the π-complex was found to not be an intermediate in the lowest energy C-H activation process. Computational studies support the conclusions and suggest that π-coordination and C-H activation of the alkene are separate and competitive pathways. We recently reported a well-defined Fe-Al complex (1) that is capable of selectively breaking the sp and sp C-H bond of pyridine substrates as well as acetonitrile. Herein we present the C-H activation in the vinylic position of styrenes using the same Fe-Al system. These reactions are highly selective resulting in a rare (E)-β-metalation of the alkenes. In contrast to single-site systems, alkene binding appears to initiate the C-H activation and is essential for the reaction to take place. An unusual reaction pathway in which a (2+2) cycloaddition intermediate is directly converted into the hydrido vinyl product is proposed. This new mechanism results in the net oxidative addition of an alkenyl sp 2 C-H bond across the two metal centers and opens new possibilities for selective alkene functionalization by C-H activation using a bimetallic approach.