Wilkinson, Sir Geofferey, 1921–, English inorganic chemist. He shared the 1973 Nobel Prize in Chemistry with Ernst Otto Fischer for their independent research on the organometallic compounds of the transitions metals. At Harvard, Wilkinson theorized that certain transition metals, such as iron and ruthenium, combine with cyclopentadienyl carbon rings to form organometallic compounds. The combination occurs in a layered arrangement in which a metallic atom is "sandwiched" between the two carbon rings. This theory initiated a vast amount of research, not only on cyclopentadienyl derivatives but on similar systems with four-, six-, seven-, and even eight-membered carbon rings.