Nickel complexes for catalytic C–H bond functionalization
The direct catalytic functionalization of traditionally unreactive C–H bonds is an atom-economic transformation that has become increasingly important and commonplace in synthetic applications. In general, 2nd and 3rd row transition metal complexes are used as catalysts in these reactions, whereas the less costly and more abundant 1st row metal complexes have limited utility. This Perspective article summarizes progress from our laboratory towards understanding the fundamental issues that complicate the use of Ni complexes for catalytic C–H bond functionalization, as well as approaches to overcoming these limitations. In practice it is found that Ni complexes can functionalize C–H bonds by processes that, to date, have not been observed with the heavier metals. An example is provided by the catalytic stannylation of C–H bonds with tributylvinyltin, Bu3SnCHCH2, which produces ethylene as a by-product.