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DuPont Central Research



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In 1957, the research organization of Chemicals Department of E. I. du Pont de Nemours and Company was renamed Central Research Department, beginning the history of the premier scientific organization within Du Pont and one of the foremost industrial laboratories devoted to basic science. Located primarily at the Experimental Station and Chestnut Run, in Wilmington, DE, it has expanded to include laboratories in Geneva, Switzerland; Seoul, South Korea; Shanghai, China; and Hyderabad, India.

The company established a tradition of basic scientific research with the polymer work of Wallace Carothers in the 1930s. This tradition waned during World War II and underwent a renaissance in the 1950s. The establishment of Central Research in 1957 formalized a corporate commitment to basic research. The execution and publication of high quality research assisted recruiting and promoted the image of the DuPont while raising morale among the CRD staff. The purpose of the research was to discover "the next nylon" - an objective that was never met. Nonetheless, another important stated goal for CRD was “diversification through research,” and CRD produced a stream of scientific innovations that contributed to many different businesses throughout the corporation.

CRD Research Directors and

Vice Presidents

Years
Paul L.Salzberg 1957-1967
David M. McQueen 1968-1971
Theodore L. Cairns 1972-1975
Howard E. Simmons, Jr. 1975-1979
Edward Lorentz 1980
Robert Naylor 1981
Charles Bottomly 1982-1983
Richard Quisenberry 1984-1992
Joseph Miller 1993-1995
James M. Meyer 1997-2000
Thomas M. Connelly 2001-2005
Uma Chowdhry 2006-present

CRD was always combined industrial and fundamental research, and the mix of the two features was often determined by the head of CR&D. The title expanded from Director of Research to Vice President of Technology to Chief Technology Officer with varying degrees of impact on research throughout the corporation as well as in CRD. The name of CRD also changed to reflect the times, starting with Chemicals Department and moving through Central Research Department (CRD), Central Research and Development Department (CR&DD), to the present Central Research and Development (CR&D). Nonetheless, it has always been called CRD by its friends.

CRD became noted for its research in a number of important areas, often requiring an interdisciplinary approach. The use of supercritical fluids is currently fashionable but DuPont’s exploration of chemical reactions in supercritical water in the 1950s supported its business in CrO2 for magnetic recording tapes. Hyperbaric recrystallization of ultra-high molecular weight polyethylene led to DuPont’s business in Hylamer polyethylene for bearing surfaces in hip and knee replacement arthroplasty. Urea and uracil compounds discovered in CRD were potent and selective herbicides, propelling DuPont into the agricultural chemicals business and culminating in sulfonylurea herbicides. Potassium titanyl phosphate or KTP is a versatile nonlinear optical material, originally designed to frequency doubling red lasers to green for bloodless laser eye surgery; it now find additional application in urological surgery and hand-held green laser pointers.

In the 1950s, the CRD housed a broad-based research program aimed largely at the synthesis and study of new classes of compounds. Synthesis of new organic and inorganic compounds accounted for about half of the total research. When the National Institute of Health invited DuPont to submit compounds to its screening efforts, they rated DuPont as submitting by far the most diverse range of compounds – pharmaceutical companies were submitting things that looked like pharmaceuticals, but Dupont submitted compounds that would be classed internally as catalysts, optical materials, monomers, oligomers, ligands, inorganics, and other unusual materials.

In addition to the synthetic efforts, CRD maintained efforts centered on new physical and analytical techniques, chemical structure and reaction mechanism studies, and solid-state physics. Of course, DuPont is well known for its strength in polymer research, and biological research has increased dramatically over the last several decades.

Until recent years, a substantial portion of research was of an academic nature. This academic research was reflected in the general atmosphere of the organization. In the late 1960s, CRD established a program for bringing postdoctoral fellows into the department. These fellowships were generally for two years and had the expectation that the fellow would leave to an academic institution. Every year one or two DuPont scientists would take one year leaves of absence for university study and teaching. It was also accepted that every year a number of scientists would leave DuPont for academic positions and that several professors would join the staff permanently. A notable example was Richard Schrock, who left CRD for MIT and won the Nobel Prize for Chemistry. The final academic connection for CRD was supported by numerous high profile consultants who have made significant contributions to DuPont. Jack Roberts of Cal Tech has consulted since 1950, enabling him to provide a perspective unavailable to (almost[1])any DuPont employee. Speed Marvel consulted for well over 50 years and provided a steady supply or well-trained polymer chemists. Robert Grubbs, who shared the Nobel Prize with Schrock, consulted for many years. These academic connections were sources of new generations of CRD researchers.

The scientific accomplishments of Theodore L. Cairns, William D. Phillips, Earl Muetterties, Howard E. Simmons, Jr., and George Parshall were recognized by their election to the National Academy of Sciences.

One of the more striking aspects of CRD is the openness with which ideas and results will be openly discussed and shared. Management has fostered the idea that success is shared, and it is better to have genuine collaboration on and contribution to a successful program than to get full credit for a less successful program. Colleagues are very accessible and helpful with problems; there is true camaraderie between scientists. At its founding, the division of labor in CRD was “management,” “bench chemists,” and “technicians,” with the management and bench chemists having separate but overlapped promotional tracks. Under the Hay Grade system of pay levels that was employed then and now, there were eight professional or promotional levels for the “bench chemists,” yet there was a single undistinguished title. This egalitarian approach promoted interaction, though it was obvious that some chemists were more equal than others.

The Hay Grades for those in management started higher and ended considerably higher, but there was significant overlap with the bench chemist levels. Thus it was not unusual for a supervisor or manager to have one or more scientists reporting to him (there were no females in management at this time) who were at higher pay levels than he was. There was one reported instance where the supervisor never got to pass pay raises to the “bench Chemist” because management didn’t want to make him feel bad; the next level Manager who did pass on the pay notification said, “They didn’t care how I felt.” Titles explicitly tied to salary level were instituted in the May, 1993, but the openness remains today as does the situation of Managers managing higher level scientists.

At the beginning of CRD, “technicians” in CRD were usually high-school educated and often had military service. They were clearly just extra hands for the bench chemists who were all PhDs and the bench chemists were expected to spend most of their time at the bench. It was virtually impossible for a technician to progress in CRD, but they could at plant sites and would sometimes move for the opportunity. Starting in the early 1990s, mostly as a result of the growth of the pharmaceutical and life science efforts, technicians with Bachelors degrees and later, Master's degrees became the norm. There are even some technicians holding PhDs from foreign universities. Nonetheless, it remains difficult for a technician to break into the bench chemist ranks and they usually transfer to business units in search of more opportunity.

Many of the PhDs who came to CRD decided that their chances for promotion and influence in the company were better if they took a different route. Just like the technicians, transferring to a business unit provides greater promotional opportunity. For a period of time from the 1980s to early 90s, there was a management effort to move all PhDs to a business unit some time in their first five years. The PhDs had spent their entire lives in an academic environment, so they knew nothing else, but it was realized that at some point they would grow up and realize that working at the bench was not what some of them would want to do their entire career. The issue was that they were too senior and naive to move into entry level positions in businesses and their competition were similarly aged BS engineers who would have had about five years of experience keeping a plant running. Many were kicked out into the real world kicking and screaming. Of those who took the opportunity, about half returned to CR&D. Of those who returned, about half left again. The relatively high turnover provided more opportunity for CRD to hire outstanding new PhDs. Transfers to business units became less common in the 1990s and the average age of CRD personnel rose considerably as a result. With baby-boomers starting to retire, there is more recruiting and there is a noticeable rejuvenation of the staff.

Responsibility for the technical direction of research has shifted to the chemist as they carry out short-term projects in support of the business units. PhDs who get MBAs are now more common. Unlike the early years, all management has had business unit experience and many were hired into business units, coming into CRD later in their careers. These managers are often far more administrative in their approach, not having the strong technical backgrounds required to keep up with their technical employees. Some managers have come to rely upon their senior technical staff, but there is no clear guideline on the role that these senior scientists can or should play in managing the programs and careers of the younger scientists.

Organfluorine Chemistry

A fluorocarbon backbone
The structural unit of Teflon®

and other fluorocarbon molecules

On April 6, 1938, Roy Plunkett at DuPont’s Jackson Laboratory in New Jersey was working with gases related to DuPont’s Freon refrigerants when he and his associates discovered that a sample of gaseous tetrafluoroethylene had polymerized spontaneously into a white, waxy solid. The polymer was polytetrafluoroethylene (PTFE) commercialized by DuPont as Teflon in 1945. Because DuPont was basic in a variety of fluorinated materials, it was logical that organofluorine chemistry became so important to DuPont. The discovery that tetrafluorethylene would cyclize with a wide variety of compounds to give fluorinated compounds having four-membered rings opened up routes to a range of organic fluorine compounds.

The hazards and difficulties of handling highly reactive and corrosive fluorinating reagents could be accommodated by DuPont’s emphasis on safety and DuPont’s association with the Manhattan Project provided many chemists and engineers with the background necessary to carry out the work. Availability of the Pressure Research Lab on the Experimental Station provided the necessary protection for most but not all of those reactions that went awry. Notable scientists included Bill Middleton, Dave England, Carl Krespan, Bill Sheppard, Owen Webster, Bruce Smart, Malli Rao, Bob Wheland, and Andy Feiring; all of the individuals on this list are among the highest patent holders in DuPont. Sheppard wrote one of the important early books on the subject.[2] Smart's book followed.[3] Smart’s comments in Chemical Reviews in 1996, “Scientific and commercial interests in fluorine chemistry burgeoned after 1980, largely fueled by the need to replace industrial chlorofluorocarbons and the rapidly growing practical opportunities for organofluorine compounds in crop protection, medicine and diverse materials applications. Although fluorine is much less abstruse now than when I entered the field a generation ago, it remains a specialized topic and most chemists are unfamiliar, or at least uncomfortable, with the synthesis and behavior of organofluorine compounds,” remain true today.

CRD undertook a program on alternatives for chlorofluorocarbons in refrigerants in the late 1970s after the first warnings of damage to stratospheric ozone were published. The Catalysis Center of CRD, under the leadership of Leo Manzer, was quick to respond with new technology to produce alternative hydrochlorofluorocarbons (HCFCs) that were commercialized as DuPont's Suva refrigerants.

Cyanocarbon Chemistry

Cyanocarbon Backbone
Structural unit of

cyanocarbon molecules.

During the 1960s and 1970s, CRD had a program under the direction of Ted Cairns to synthesize long-chain cyanocarbons analogous to long-chain fluorocarbons like Teflon®. The work culminated in a series of twelve papers in the Journal of the American Chemical Society in 1958 that are a tour de force of academic chemistry. The list of authors of those papers reads like a Who’s Who of future CRD and DuPont management,[4] indicating the importance of technical qualification for promotion in the company at that time. The publication stimulated other researchers to investigate these compounds.
DISN

Diiminosuccinonitrile

DAMN

Diaminomaleonitrile

Prospective applications included dyes, pharmaceuticals, pesticides, organic magnets, and incorporation in new types of polymers. Unfortunately no practical commercial applications resulted from this extensive research effort. Partly for this work, Cairns was awarded medals for Creative Work in Synthetic Organic Chemistry by the American Chemical Society and the Synthetic Organic Award of the Chemicals Manufacturers Association. Another line of chemistry developed around Owen Webster’s synthesis of diiminosuccinonitrile (DISN) that could be converted to diaminomaleonitrile (DAMN) leading to another series of patent and papers. Simmons used disodium dimercaptomaleonitrile for the preparation many novel substances of including tetracyanothiophene, tetracyanopyrrole, and pentacyanocyclopentadiene.

Metal oxides

Arthur Sleight led a team focused on perovskites, such as the K-Bi-Pb-O system, that laid the ground work for subsequent breakthroughs in high-temperature superconductors.[5] In solution phase chemistry of oxides, the work of Walter Knoth on organic soluble polyoxoanions led to the development of the now large area with numerous applications in oxidation catalysis.[6]

Dynamic NMR Spectroscopy

Indicative of interplay between applications and fundamental science were many studies on stereodynamics conducted at CRD by Jesson, Meakin, and Muetterties. One of the early studies focused on the non-rigidity of SF4, a reagent relevant to the preparation of fluorocarbons. Subsequent studies led to the discovery of the first stereochemically non-rigid octahedal complexes of the type FeH2(PR3)4.[7]

Polymer Science

Owen Webster discovered group-transfer polymerization (GTP), the first new polymerization process developed since living anionic polymerization. The major aspects of the mechanism of the reaction were determined and the process was quickly converted to commercial application for automotive finishes and ink jet inks. The basic process of group transfer also has application to general organic synthesis, including natural products.[8]

At about the same time, Andrew Janowicz developed a useful version of cobalt catalyzed chain transfer for controlling the molecular weight of free radicalpolymerizations. The technology has been further developed by Alexei Gridnev and Steven Ittel. It, too, was quickly commercialized and a fundamental understanding of the process developed over a longer period of time.[9]

Rudolph Pariser was the director of the Advanced Materials Science and Engineering at the time of these advances.

In 1995, Maurice Brookhart, professor at the University of North Carolina and a DuPont CRD consultant, invented a new generation of post-metallocene catalysts for olefin coordination polymerization based upon late transition metals with his postdoctoral student, Lynda Johnson who later joined CRD.[10] The technology, DuPont’s Versipol® olefin polymerization technology, was developed by a substantial team of CRD scientists over the next ten years.

Organometallic Chemistry

Cramer’s Dimer
Tebbe Reagent

CRD developed a major interest in inorganic and organometallic chemistry. Earl Muetterties established a program aimed at fundamental borane chemistry.[11] 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.[12] Norman Miller discovered the B12H12= anion in an effort to find a new route to B10H10=.[13] 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 lead 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”[14] that has become the standard reference on the subject.

The seminal contributions of Richard Cramer and Frederick 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 J. Arduengo, III’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. Chadwick Tolman developed his “ligand cone angle” theory that developed into the widely accepted electronic and steric effects of ligands on inorganic and organometallic complexes.[15]

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,[16] 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.

Photochemsitry and Physics

David M. McQueen, one of the early Directors of CRD was a physical chemist from the University of Wisconsin-Madison. His research on photochemistry and photography resulted in thirty-five patents. It was his background that got CRD started in photochemistry and photophysics. David Eaton later headed a strong team involved in photopolymerization color proofing for the printing industry.

There was a strong program in inorganic non-linear optical materials that resulted in optical frequency doubling for the “green lasers” mentioned above. This program was extended into organic materials with NLO properties.

There was also a strong effort on materials for the display industry and methods for preparing devices for displays. These included printable electronics, thermal transfer methods for color filters, carbon nanotubes for field emission displays, and OLED materials and devices. A substantial effort was made on next generation photoresists for the semiconductor industry containing hydrocarbon and fluorocarbon monomers to replace wavelengths of 193 nm with 157 nm wavelengths for better resolution. Though most of the requirements were achieved, the need for that shorter wavelength node was eliminated by the introduction of immersion lithography and new fluids for immersion lithography continue to be of substantial interest. Development of phase-shift masks was commercialized.

Biological Sciences

One area always deemed important for diversification of CRD's programs was related to the biological sciences. Charles Stine had promoted biochemistry as a field of research for Du Pont and Stine Laboratories are named in his honor as a result. In the early 1950s, CRD began a program to investigate chemicals for biological applications. Charles Todd prepared substituted ureas as potential antibacterial agents, which when screened, proved to be effective herbicides. These led to DuPont’s very successful and very selective sulfonylurea herbicides. CRD's program included agricultural and veterinary chemicals and bacteriological and microbiological studies. The culmination of this work was DuPont’s purchase of Pioneer Hi-Bred Seeds and its integration into DuPont’s agrichemical enterprise.

In the mid- 1950s, CRD began work on the chemistry of nitrogen fixation in plants, a study that would develop into a major effort over the next decade. In 1963, Ralph Hardy joined the CRD and brought Du Pont's nitrogen fixation research to international prominence with more than a hundred papers on the subject. Chemical Week called him, "one of the nation's top achievers in the dual role of scientist and scientific manager," though such managers remained common in CRD through the 1960s and 70s.

Fermentation microbiology and selective genetic modification became important to the CRD development of a biological route to 1,3-propylene glycol a new monomer for making polyester. The availability of this new monomer led to the development and commercialization of Sorona, a premium polyester. Substantial success was also achieved in the synthesis of unnatural peptides and proteins to accomplish specific functions and prediction of their tertiary structures.

Advances in DNA sequencing technology based on synthesis of novel fluorescent labels led to Qualicon, a DuPont venture that identifies bacteria by examination of their DNA using PCR. This technology has led to significant improvements in the safety of the food supply chain in the United States and around the world.

How it was through the years - Unreferenced reminiscences of several CRD alumni.

The 1950s The 1970s The 2000s
It was a PhD-centered culture. It was a PhD-centered culture. It is a PhD-centered culture.
Chemist wore white shirts and ties in the lab. No beards. No jeans. Beards. Jeans. It was the 70s, even at DuPont. Management identified by ties. The rare tie means that one has an important customer that day.
Synthetic chemistry prevails. Synthetic chemistry strong with physics and biology starting Synthetic chemistry serves development with strong biological program at forefront.
Chemists ran most of the reactions. Technicians and chemists ran reactions. A few technicians had notebooks. Technicians run most reactions. Chemists and technicians share electronic notebooks.
Very few female chemists. The few female chemists tended to move out of the lab into business positions. Female chemists are well represented at all levels.
Clay Smith and Wes Memeger, the first minority employees, started in the mid 60s. There few minority employees despite an effort to recruit more. Minorities are well represented though black male chemists are still under-represented.
Technicians had high school degrees and washed dishes and got things from the store room. Dish-washers moved from lab to lab and got things from the store room. BS and MS technicians washed dishes and got things from the store room.
Several female Technicians left over from the War years, but few new ones were hired until 1965. Female Technicians were a minority. Male and female Technicians are in equal numbers.
Secretaries were not allowed in the labs. Secretaries took dictation. Secretaries supported a single work group. Secretaries typed all reports and might take dictation from Managers. Office support staff support large groups. Chemists type all of their own work in Word and PowerPoint.
Idea and literature group meetings once a week. Group meeting once a week to discuss technical progress. Weekly or biweekly team meetings to discuss progress against business milestones.
Each scientist had one or two programs. There could be more than one person on a program, but fractional programs were also common. Substantial teams assigned to a few major projects.
Library girls looked up thing for you in the library. Journals circulated to scientist’s desks. Journals available online.
Weekly reports from library reviewed what was published. CAS was online. Professional literature searchers did the tough searches and patent work. SciFinder to search CAS online. Literature searchers did the patent searches.
Presentations were done with charts made by the drawing room and converted to black and white 35mm slides in the photo shop. Presentations were done with charts made on a computer and converted to 35mm slides in the photo shop. Presentations were done and shown in PowerPoint.
Instruments included IR's but no NMR's nor commercial GC's. When GC came, columns were packed by hanging them in the stairwell and vibrating them as the packing was poured in 4 stories up. IRs and GCs were common. NMRs were 60 and 90 MHz with the first commercial Varian 220 MHz instrument. HPLCs and GC/MSs were common. NMRs were 300 and 400 MHz with 600 MHz available.
Two Progress reports per year were expected. These were archived and indexed by hand in card files. One Progress Report per year was expected and was indexed privately for DuPont by CAS. One Progress Report per year was hoped for, but information also went into numerous databases.
Publications were expected. Publications were appreciated. Publications were accepted.
CRD was hiring. There was little hiring. Down-sizing, right-sizing, layoffs were starting.

General References

  • David A. Hounshell and John Kenley Smith. Science and Corporate Strategy. DuPont R&D, 1902-1980. New York: Cambridge University Press, 1988.
  • J. J. Bohning. Howard E. Simmons, Jr., Oral History. Philadelphia: Chemical Heritage Foundation, 1993.
  • R. C. Ferguson. William D. Phillips and nuclear magnetic resonance at DuPont. In Encyclopedia of Nuclear Magnetic Resonance, Vol. 1, Eds. D. M. Grant and R. K. Harris, pp. 309-13, John Wiley & Sons, 1996.
  • R. G. Bergman, G. W. Parshall, and K. N. Raymond. Earl L. Muetterties, 1927-1984. In Biographical Memoirs, vol. 63, pp. 383-93. Washington, D.C.: National Academy Press, 1994.
  • B. C. McKusick and Theodore L. Cairns, Cyanocarbons in Kirk-Othmer Encyclopedia of Chemical Technology, 2nd Edition, 6, 625-33 (1965)

References

  1. ^ Edward Howard started with DuPont before 1950 and continues to work as a CRD employee, though only three days a week. His DuPont patents span a period of over 50 years. From Edward G. Howard, Jr., Catalyst system of bromate ion-sulfoxy compounds for use in aqueous polymerization processes, US 2560694 (1951) through Dennis Edward Curtin, and Edward George Howard, Compositions containing particles of highly fluorinated ion exchange polymer US7166685 B2 (2007), with about 100 patents between.
  2. ^ William A. Sheppard and Clay M. Sharts, Organic Fluorine Chemistry, 1969, W. A. Benjamin, Inc.
  3. ^ R.E. Banks, B.E. Smart, and J.C. Tatlow, Organofluorine Chemistry: Principles and Commercial Applications (Topics in Applied Chemistry), Springer (New York); 1 edition (September 30, 1994).
  4. ^ Cyanocarbon authors who progressed in DuPont management include: Richard E. Benson - Associate Director, CRD; Theodore L. Cairns - Research Director, CRD; Richard E. Heckert – CEO of DuPont; William D. Phillips - Associate Director, CRD; Howard E. Simmons - Research Director and VP, CRD; and Susan A. Vladuchick - Plant Manager.
  5. ^ Sleight, A. W.; Gillson, J. L.; Bierstedt, P. E. High-temperature superconductivity in the barium plumbate bismuthate (BaPb1-xBixO3) systems. Solid State Communications (1975), 17(1), 27-8. Sleight, Arthur W. Superconductive barium-lead-bismuth oxides. U.S. Patent 3932315 (1976). Sleight, Arthur W. Newer superconductors. CHEMTECH (1976), 6(7), 468-70.
  6. ^ Knoth, W. H.; Domaille, P. J.; Harlow, R. L. Heteropolyanions of the types M3(W9PO34)212- and MM'M"(W9PO34)212-: novel coordination of nitrate and nitrite. Inorganic Chemistry (1986), 25(10), 1577-84. Knoth, W. H.. Derivatives of heteropolyanions. 1. Organic derivatives of W12SiO404-, W12PO403-, and Mo12SiO404-. Journal of the American Chemical Society (1979), 101(3), 759-60.
  7. ^ Meakin, P. Muetterties, E. L.; Jesson, J. P. "Stereochemically Nonrigid Six-Coordinate Molecules. III. The Temperature-Dependent 1H and 31P Nuclear Magnetic Resonance Studies of Some Iron and Ruthenium Dihydrides" Journal of the American Chemical Society 1973, 95, pp 75-87.
  8. ^ O. W. Webster and coworkers, Group-transfer polymerization. 1. A new concept for addition polymerization with silicon initiators. J. Am. Chem. Soc. 105(1983):5706-5708.
  9. ^ Alexei I. Gridnev and Steven D. Ittel, Chemical Reviews, 101, 3611-3659 (2001).
  10. ^ Steven D. Ittel, Lynda K. Johnson and Maurice Brookhart, Late-Metal Catalysts for Ethylene Homo- and Copolymerization, Chemical Reviews, 100, 1169-1203, 2000.
  11. ^ Knoth, W. H.; Miller, H. C.; England, D. C.; Parshall, G. W.; Muetterties, E. L. Derivative chemistry of B10H10-- and B12H12--. Journal of the American Chemical Society (1962), 84 1056-7.
  12. ^ Knoth, Walter H., Jr. Ionic boron compounds. U.S. Patent 3390966 (1968). Knoth, Walter H., Jr. Neutral and singly charged derivatives of decaboranes and decaborates. U.S. Patent 3296260 (1967).
  13. ^ Knoth, Walter H. Jr.; Miller, Norman Earl. Salts of polyhedral polyborates. U.S. Patent 3334136 (1967).
  14. ^ G. W. Parshall and S. D. Ittel, Homogeneous Catalysis, 2nd Edition, Wiley Interscience, 1992.
  15. ^ C. A. Tolman, Steric Effects of Phosphorus Ligands in Organometallic Chemistry and Homogeneous Catalysis, Chemical Reviews, 1977, volume 77, pages 313-48.
  16. ^ William A. Nugent and James M. Mayer, Metal-Ligand Multiple Bonds: The Chemistry of Transition Metal Complexes Containing Oxo, Nitrido, Imido, Alkylidene, or Alkylidyne Ligands, Wiley-Interscience; 1 edition (October 31, 1988)
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "DuPont_Central_Research". A list of authors is available in Wikipedia.
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