Russell P. Hughes

Last updated

Russell P. Hughes (born December 23, 1946) an American/British chemist, is the Frank R. Mori Professor Emeritus and Research Professor in the Department of Chemistry at Dartmouth College. His research interests are in organometallic chemistry, with emphasis on the chemistry of transition metal complexes interacting with fluorocarbons. His research group’s work in this area led to several creative syntheses of complexes of transition metal and perfluorinated hydrocarbon fragments. [1]

Contents

Education

Hughes was born on December 23, 1946, in Denbigh, Wales, the son of Elliot and Joan (Profit) Hughes. He became interested in Chemistry at Ecclesfield Grammar School, near Sheffield, under the tutelage of inspiring teacher Stanley Spencer. He earned his B.Sc. at the University of Manchester Institute of Science and Technology, and his Ph.D. at the University of Toronto under John Powell. He held postdoctoral fellowships at the University of Bristol in Michael Green's laboratory and at McGill University with John Harrod. [2]

Research career

Hughes began his independent scientific career as an assistant professor at Dartmouth College in 1976. He was promoted to Associate Professor in 1982, and Professor in 1986. He chaired the department of Chemistry from 1991 to 1994. In 1999, he was appointed to be the Inaugural Frank R. Mori Professor in the Arts & Sciences. His research has centered on organometallic chemistry, with focus on the chemistry of transition metal complexes interacting with fluorocarbons and the organometallic chemistry of small organic rings. [1] After 35 years of experimental work, he transitioned to computational chemistry and collaborative research. [2]

Honors

Hughes is a Fellow of the Alfred P. Sloan Foundation, the American Chemical Society, the American Association for the Advancement of Science, the Alexander von Humboldt Foundation, and the Royal Society of Chemistry. He was awarded a Doctor of Science degree for his independent published research work by the University of Manchester in 1990. The American Chemical Society gave him its Award for Creative Work in Fluorine Chemistry in 2010. [2]

In 2002, Hughes received the Dartmouth Student Assembly’s “Profile in Excellence” Teaching Award. On his retirement from teaching in 2015, he was awarded the Elizabeth Howland Hand - Otis Norton Pierce Award. [ citation needed ]

Research highlights

Metal Complexes of Octafluorocyclooctatetraene (OFCOT)

One of Hughes’ research interests focused on the study of transition metal complexes with octafluorocyclooctatetraene (OFCOT), and the comparison of the structural features of these complexes to the hydrocarbon counterpart of OFCOT cyclooctatetraene (COT). [3] One striking difference in the coordination complexes of OFCOT is that their thermal stability and resistance to undergo dynamic rearrangements in binding geometry (reduced fluxional character) are greatly enhanced compared to COT analogs. [1] These differences can be rationalized based on the relative thermodynamic stability of the isomers computed using density functional theory (DFT). [1]

Differences in interactions of transition metals with cyclooctatetraene (COT) vs octafluorocyclooctatetraene (OFCOT) Octafluorocyclooctatetraene.png
Differences in interactions of transition metals with cyclooctatetraene (COT) vs octafluorocyclooctatetraene (OFCOT)

First Transition Metal Complexes Containing Perfluorocyclopentadienyl Ligand

In 1992, Hughes and coworkers reported a creative use of flash vacuum pyrolysis (at 770 °C) to extrude CO from an oxacyclohexadienyl complex led to the first metallocene containing a perfluorinated cyclopentadienyl ring, η5-C5F5. [4] Direct comparison of the ruthenocene to its perfluorocyclopentadienyl analog enabled direct insight into the structural similarities and differences of the two compounds. [5] It was observed that the C5F5 interaction with Ru results in a shorter distance between this ring and Ru, compared to the hydrocarbon analog. [5]

Structural differences in ruthenocene to its perfluorocyclopentadienyl analog Ruthenocene and its perfluorocyclopentadienyl analog.png
Structural differences in ruthenocene to its perfluorocyclopentadienyl analog

Perfluorobenzyne Complex

In 2001, through dehydrofluorination of an iridium complex bearing perfluorophenyl and hydride groups, Hughes and coworkers synthesized to the first transition metal complex of perfluorobenzyne (C6F4). [6]

perfluorobenzyne Perfluorobenzyne.png
perfluorobenzyne

Perfluorocarbene Complexes

In 2005, through an inner-sphere reduction reaction of perfluoroalkyl ligands Hughes and coworkers provided a novel and useful route to difluorocarbene and perfluoroalkylidene complexes. [7] This was followed in 2007 by the synthesis of the first, and so far, the only, example of a carbene ligand bearing two strongly electron withdrawing perfluoroalkyl groups. [8]

perfluorocarbene complex Perfluorocarbene Complex.png
perfluorocarbene complex

The Simplest Fluorocarbon as Ligand

In 2006, Hughes and coworkers showed that even the simplest possible fluorocarbon fragment, CF, stabilized by a triple bond to molybdenum, could be prepared by reduction of a Mo-trifluoromethyl complex. [9]

simplest fluorocarbon as ligand Simplest fluorocarbon as ligand.png
simplest fluorocarbon as ligand

Related Research Articles

<span class="mw-page-title-main">Robert H. Crabtree</span> British-American chemist

Robert Howard Crabtree is a British-American chemist. He is serving as Conkey P. Whitehead Professor Emeritus of Chemistry at Yale University in the United States. He is a naturalized citizen of the United States. Crabtree is particularly known for his work on "Crabtree's catalyst" for hydrogenations, and his textbook on organometallic chemistry.

Organofluorine chemistry describes the chemistry of organofluorine compounds, organic compounds that contain a carbon–fluorine bond. Organofluorine compounds find diverse applications ranging from oil and water repellents to pharmaceuticals, refrigerants, and reagents in catalysis. In addition to these applications, some organofluorine compounds are pollutants because of their contributions to ozone depletion, global warming, bioaccumulation, and toxicity. The area of organofluorine chemistry often requires special techniques associated with the handling of fluorinating agents.

<span class="mw-page-title-main">Dimanganese decacarbonyl</span> Chemical compound

Dimanganese decacarbonyl, which has the chemical formula Mn2(CO)10, is a binary bimetallic carbonyl complex centered around the first row transition metal manganese. The first reported synthesis of Mn2(CO)10 was in 1954 at Linde Air Products Company and was performed by Brimm, Lynch, and Sesny. Their hypothesis about, and synthesis of, dimanganese decacarbonyl was fundamentally guided by the previously known dirhenium decacarbonyl (Re2(CO)10), the heavy atom analogue of Mn2(CO)10. Since its first synthesis, Mn2(CO)10 has been use sparingly as a reagent in the synthesis of other chemical species, but has found the most use as a simple system on which to study fundamental chemical and physical phenomena, most notably, the metal-metal bond. Dimanganese decacarbonyl is also used as a classic example to reinforce fundamental topics in organometallic chemistry like d-electron count, the 18-electron rule, oxidation state, valency, and the isolobal analogy.

<span class="mw-page-title-main">Transition metal dinitrogen complex</span> Coordination compounds with N2

Transition metal dinitrogen complexes are coordination compounds that contain transition metals as ion centers the dinitrogen molecules (N2) as ligands.

Transition metal carbyne complexes are organometallic compounds with a triple bond between carbon and the transition metal. This triple bond consists of a σ-bond and two π-bonds. The HOMO of the carbyne ligand interacts with the LUMO of the metal to create the σ-bond. The two π-bonds are formed when the two HOMO orbitals of the metal back-donate to the LUMO of the carbyne. They are also called metal alkylidynes—the carbon is a carbyne ligand. Such compounds are useful in organic synthesis of alkynes and nitriles. They have been the focus on much fundamental research.

<span class="mw-page-title-main">Boranylium ions</span>

In chemistry, a boranylium ion is an inorganic cation with the chemical formula BR+
2
, where R represents a non-specific substituent. Being electron-deficient, boranylium ions form adducts with Lewis bases. Boranylium ions have historical names that depend on the number of coordinated ligands:

<span class="mw-page-title-main">Jaqueline Kiplinger</span> American inorganic chemist

Jaqueline Kiplinger is an American inorganic chemist who specializes in organometallic actinide chemistry. Over the course of her career, she has done extensive work with fluorocarbons and actinides. She is currently a Fellow of the Materials Synthesis and Integrated Devices group in the Materials Physics and Applications Division of Los Alamos National Laboratory (LANL). Her current research interests are focused on the development of chemistry for the United States’ national defense and energy needs.

David Markham Lemal is the Albert W. Smith Professor of Chemistry Emeritus and Research Professor of Chemistry at Dartmouth College. He received an A.B. degree (summa) from Amherst College in 1955 and a Ph.D. in chemistry from Harvard University in 1959. At Harvard he worked with R. B. Woodward on deoxy sugars and a synthesis of the alkaloid yohimbine.

In chemistry, compounds of palladium(III) feature the noble metal palladium in the unusual +3 oxidation state (in most of its compounds, palladium has the oxidation state II). Compounds of Pd(III) occur in mononuclear and dinuclear forms. Palladium(III) is most often invoked, not observed in mechanistic organometallic chemistry.

The Mukaiyama hydration is an organic reaction involving formal addition of an equivalent of water across an olefin by the action of catalytic bis(acetylacetonato)cobalt(II) complex, phenylsilane and atmospheric oxygen to produce an alcohol with Markovnikov selectivity.

<span class="mw-page-title-main">Phosphenium</span> Divalent cations of phosphorus

Phosphenium ions, not to be confused with phosphonium or phosphirenium, are divalent cations of phosphorus of the form [PR2]+. Phosphenium ions have long been proposed as reaction intermediates.

<span class="mw-page-title-main">Lanthanocene</span>

A lanthanocene is a type of metallocene compound that contains an element from the lanthanide series. The most common lanthanocene complexes contain two cyclopentadienyl anions and an X type ligand, usually hydride or alkyl ligand.

β-Carbon elimination is a type of reaction in organometallic chemistry wherein an allyl ligand bonded to a metal center is broken into the corresponding metal-bonded alkyl (aryl) ligand and an alkene. It is a subgroup of elimination reactions. Though less common and less understood than β-hydride elimination, it is an important step involved in some olefin polymerization processes and transition-metal-catalyzed organic reactions.

Concerted metalation-deprotonation (CMD) is a mechanistic pathway through which transition-metal catalyzed C–H activation reactions can take place. In a CMD pathway, the C–H bond of the substrate is cleaved and the new C–Metal bond forms through a single transition state. This process does not go through a metal species that is bound to the cleaved hydrogen atom. Instead, a carboxylate or carbonate base deprotonates the substrate. The first proposal of a concerted metalation deprotonation pathway was by S. Winstein and T. G. Traylor in 1955 for the acetolysis of diphenylmercury. It was found to be the lowest energy transition state in a number of computational studies, was experimentally confirmed through NMR experiments, and has been hypothesized to occur in mechanistic studies.

Jonas C. Peters is the Bren Professor of Chemistry at the California Institute of Technology and Director of the Resnick Sustainability Institute. He has contributed to the development of catalysts and photocatalysts relevant to small molecule activation.

Metal-ligand cooperativity (MLC) is a mode of reactivity in which a metal and ligand of a complex are both involved in the bond breaking or bond formation of a substrate during the course of a reaction. This ligand is an actor ligand rather than a spectator, and the reaction is generally only deemed to contain MLC if the actor ligand is doing more than leaving to provide an open coordination site. MLC is also referred to as "metal-ligand bifunctional catalysis." Note that MLC is not to be confused with cooperative binding.

Karsten Meyer is a German inorganic chemist and Chair of Inorganic and General Chemistry at the Friedrich-Alexander University of Erlangen-Nürnberg (FAU). His research involves the coordination chemistry of transition metals as well as uranium coordination chemistry, small molecule activation with these coordination complexes, and the synthesis of new chelating ligands. He is the 2017 recipient of the Elhuyar-Goldschmidt Award of the Spanish Royal Society of Chemistry, the Ludwig-Mond Award of the Royal Society of Chemistry, and the L.A. Chugaev Commemorative Medal of the Russian Academy of Sciences, among other awards. He also serves as an Associate Editor of the journal Organometallics since 2014.

<span class="mw-page-title-main">Paula Diaconescu</span> Inorganic chemist

Paula L. Diaconescu is a Romanian-American chemistry professor at the University of California, Los Angeles. She is known for her research on the synthesis of redox active transition metal complexes, the synthesis of lanthanide complexes, metal-induced small molecule activation, and polymerization reactions. She is a fellow of the American Association for the Advancement of Science.

A molecular electron-reservoir complex is one of a class of redox-active systems which can store and transfer electrons stoichiometrically or catalytically without decomposition. The concept of electron-reservoir complexes was introduced by the work of French chemist, Didier Astruc. From Astruc's discoveries, a whole family of thermally stable, neutral, 19-electron iron(I) organometallic complexes were isolated and characterized, and found to have applications in redox catalysis and electrocatalysis. The following page is a reflection of the prototypal electron-reservoir complexes discovered by Didier Astruc.

A metal-formaldehyde complex is a coordination complex in which a formaldehyde ligand has two bonds to the metal atom(s) (η2-CH2O). This type of ligand has been reported in both monometallic and bimetallic complexes.

References

  1. 1 2 3 4 Hughes, Russell P. (2010-11-01). "Fluorine as a ligand substituent in organometallic chemistry: A second chance and a second research career". Journal of Fluorine Chemistry. 2010 ACS Award Issue "For Creative Work in Fluorine Chemistry" Russell P. Hughes. 131 (11): 1059–1070. doi:10.1016/j.jfluchem.2010.06.014.
  2. 1 2 3 Archived 2016-12-20 at the Wayback Machine Faculty page at Dartmouth>
  3. Barefoot, Aldos C.; Corcoran, Edward W.; Hughes, Russell P.; Lemal, David M.; Saunders, W. Daniel; Laird, Brian B.; Davis, Raymond E. (1981-02-01). "Octafluorocyclooctatetraene transition-metal chemistry: 1,2-.eta. and 1,2,3,6-.eta. complexes of iron and platinum". Journal of the American Chemical Society. 103 (4): 970–972. doi:10.1021/ja00394a057. ISSN   0002-7863.
  4. Curnow, Owen J.; Hughes, Russell P. (1992-07-01). "[Ru(.eta.5-C5Me5)(.eta.5-C5F5)]: the first transition-metal complex containing a perfluorocyclopentadienyl ligand". Journal of the American Chemical Society. 114 (14): 5895–5897. doi:10.1021/ja00040a083. ISSN   0002-7863.
  5. 1 2 Hughes, Russell P.; Zheng, Xiaoming; Ostrander, Robert L.; Rheingold, Arnold L. (1994-05-01). "Synthesis and Molecular Structure of [Ru(.eta.5-C5H5)(.eta.5-C5F5)]. Intramolecular Structural Comparison of the Cyclopentadienyl Ligand with its Perfluorinated Analog". Organometallics. 13 (5): 1567–1568. doi:10.1021/om00017a011. ISSN   0276-7333.
  6. Hughes, Russell P.; Williamson, Alex; Sommer, Roger D.; Rheingold, Arnold L. (2001-08-01). "The First Transition Metal Complex of Tetrafluorobenzyne: Ir(η5-C5Me5)(PMe3)(η2-C6F4)". Journal of the American Chemical Society. 123 (30): 7443–7444. doi:10.1021/ja010992o. ISSN   0002-7863. PMID   11472184.
  7. Hughes, Russell P.; Laritchev, Roman B.; Yuan, Jian; Golen, James A.; Rucker, Adam N.; Rheingold, Arnold L. (2005-11-01). "A Simple Route to Difluorocarbene and Perfluoroalkylidene Complexes of Iridium". Journal of the American Chemical Society. 127 (43): 15020–15021. doi:10.1021/ja055166k. ISSN   0002-7863. PMID   16248629.
  8. Yuan, Jian; Hughes, Russell P.; Rheingold, Arnold L. (2007-10-01). "The First Example of a Bis(trifluoromethyl)carbene Transition-Metal Complex and Its Reduction to a Perfluoroallene Complex". European Journal of Inorganic Chemistry. 2007 (30): 4723–4725. doi:10.1002/ejic.200700814. ISSN   1099-0682.
  9. Huang, Hui; Hughes, Russell P.; Landis, Clark R.; Rheingold, Arnold L. (2006-06-01). "The Simplest Binary Fluorocarbon as a Ligand. Synthetic, Spectroscopic, Crystallographic, and Computational Studies of a Molybdenum Complex of Terminally Ligated Carbon Monofluoride (Fluoromethylidyne)". Journal of the American Chemical Society. 128 (23): 7454–7455. doi:10.1021/ja062510k. ISSN   0002-7863. PMID   16756295.