Du Pont Central Research - Organometallic Chemistry

Organometallic Chemistry

CRD developed a major interest in inorganic and organometallic chemistry. Earl Muetterties established a program aimed at fundamental borane chemistry. Walter Knoth discovered the first polyhedral borane anion, B₁₀H₁₀=, and also discovered that the borane anions displayed a substitution chemistry similar to that of aromatic hydrocarbons. Norman Miller discovered the B₁₂H₁₂= anion in an effort to find a new route to B₁₀H₁₀=. George Parshall joined CRD in 1954. His industrial sabbatical at Imperial College London with Geoffrey Wilkinson in 1960-61 introduced him to organometallic chemistry. Muetterties left DuPont to join the faculty of Cornell in 1973. After Muetterties and Parshall, the organometallic chemistry group was led by Steven Ittel and then Henry Bryndza before it was dispersed throughout a number of groups in CRD. Parshall and Ittel coauthored a book on “Homogeneous Catalysis” that has become the standard reference on the subject.

The seminal contributions of Richard Cramer and Fred Tebbe are acknowledged by their named compounds, “Cramer’s dimer,” Rh₂Cl₂(C₂H₄)₄, and the “Tebbe reagent.” Tebbe had an influence on his lab partner, Richard Schrock who initiated a program on M=C chemistry at DuPont and continued it when he moved to MIT. The chemistry forms the basis for olefin metathesis, and Schrock ultimately shared the Nobel Prize with Robert Grubbs, a CRD consultant, for the metathesis work. Anthony Arduengo’s persistent carbenes opened up a new area of chemistry and they have proven to be important ligands in the metathesis process.

There was a vigorous effort on the activation of C-H bonds with contributions by Parshall, Thomas Herskovitz, Ittel, and David Thorn. Chad Tolman developed his “ligand cone angle” theory that developed into the widely accepted electronic and steric effects of ligands on inorganic and organometallic complexes.

Organometallic chemistry in CRD has further included R. Thomas Baker's heterobinuclear complexes, Patricia L. Watson's organolanthanides, William A. Nugent's metal-ligand multiple bonds, Jeffery Thompson's and Mani Subramanyam's development of technetium complexes for radiopharmaceuticals, and Bob Burch's and Karin Karel's fluoro-organometallic chemistry. The major outlet for organometallic chemistry is homogeneous catalysis. DuPont developed a major technology based upon the nickel catalyzed addition of two molecules of hydrogen cyanide to butadiene, giving adiponitrile, a nylon intermediate. The mechanistic work to provide an understanding of the technology was done in CRD and led to a large program on next-generation technology before the business was sold to Koch Industries. Other applications of homogeneous catalysis studied in CRD include ethylene polymerization, cyclohexane oxidation to adipic acid, and butadiene carbonylation to nylon intermediates. Approaches to catalyst systems have included homogeneous organometallic catalysts, heterobinuclear catalysts, polyoxometalates, enzymes, catalytic membrane reactors and supported organometallics.