Henry Gilman:  American Pioneer in the Rise of Organometallic Chemistry in Modern Science and Technology (2002)

The growth and development of organometallic chemistry from an esoteric, well-nigh alchemical art into a completely integrated and essential part of both current organic chemistry and inorganic chemistry have occurred with escalating rapidity over the last 150 years. The sesquicentennial history of organometallic chemistry falls rather naturally into three 50-year periods, each of which began with far-reaching discoveries: (1) the discovery of zinc alkyls by Frankland in 1849 and the use of such alkyls to prepare alkyls of other metals; (2) the discovery of organomagnesium halides by Grignard in 1900 and their many reactions with organic compounds; and (3) the dual discoveries of the existence and structure of ferrocene by Pauson and Miller in 1951 and of the polymerization of olefins by Ziegler and Natta in 1952−1953. The marked burgeoning of organometallic chemistry after World War I is traced to an international group of young pioneers launching their careers with high hope and vigor: Gilman, Kharasch, Ziegler, Wittig, Kipping, Pope, Grignard and his school, Nesmeyanov, and Razuvaev. The thesis of this historical review is that Henry Gilman, through the breadth and depth of his numerous, original contributions on covalent, σ-bonded organometallics, is the one pioneer of this group who has integrated and systematized the great lode of empirical observations on organometallics into correlations with the metal's position in a Mendeleevian periodic table. He has thereby transformed this field from alchemical art into chemical science. In support of this thesis of Henry Gilman as the prototypical pioneer of modern organometallic chemistry, this account traces his academic career at Iowa State and points out his scientific contributions made at successive stages: (1) his studies of the Grignard reagents, which did much to make their preparation convenient and reliable and their reactions of broad and useful scope; (2) his investigations of organolithium reagents and his discovery and key development of the lithium−hydrogen and lithium−halogen exchange processes, which reactions were studied independently by Karl Ziegler and by Georg Wittig but merit being termed the Gilman lithium−hydrogen exchange and the Gilman−Wittig lithium−halogen exchange reactions, respectively; (3) the preparation and reactions of many other organometallics, obtained by the transmetalation reaction of the appropriate metal salts with a magnesium or lithium organometallic; and (4) finally the preparation, structure, and chemical reactivity of diverse organometallics of group 14, especially those with metal−metal and metal−alkali metal bonds. It can be argued with great cogency that such a lifetime of research set the stage and drew the curtail for the dawn of the third era of organometallic chemistry: the discovery and utility of π-bonded organometallics. Because of Gilman's towering role in uncovering, developing, and systematizing the chemistry of σ-bonded organometallics, many of Gilman's colleagues and former students had thought him deserving of chemistry's highest honor.