High-Spin Cobalt Hydrides for Catalysis

High-Spin Cobalt Hydrides for Catalysis

Date: August 29, 2013
Creator: Holland, Patrick L.
Description: Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the ...
Contributing Partner: UNT Libraries Government Documents Department
Cooperativity Between Low-Valent Iron and Potassium Promoters in Dinitrogen Fixation

Cooperativity Between Low-Valent Iron and Potassium Promoters in Dinitrogen Fixation

Date: June 26, 2012
Creator: Figg, Travis M.; Holland, Patrick L. & Cundari, Thomas R., 1964-
Description: Article discussing the cooperativity between low-valent iron and potassium promoters in dinitrogen fixation.
Contributing Partner: UNT College of Arts and Sciences
Electronically Unsaturated Three-Coordinate Chloride and Methyl Complexes of Iron, Cobalt, and Nickel

Electronically Unsaturated Three-Coordinate Chloride and Methyl Complexes of Iron, Cobalt, and Nickel

Date: November 8, 2002
Creator: Holland, Patrick L.; Cundari, Thomas R., 1964-; Perez, Lanyn L.; Eckert, Nathan A. & Lachicotte, Rene J.
Description: This article discusses electronically unsaturated three-coordinate chloride and methyl complexes of iron, cobalt, and nickel.
Contributing Partner: UNT College of Arts and Sciences
A T-Shaped Three-Coordinate Nickel(l) Carbonyl Complex and the Geometric Preferences of Three-Coordinate d9 Complexes

A T-Shaped Three-Coordinate Nickel(l) Carbonyl Complex and the Geometric Preferences of Three-Coordinate d9 Complexes

Date: October 5, 2005
Creator: Eckert, Nathan A.; Dinescu, Adriana; Cundari, Thomas R., 1964- & Holland, Patrick L.
Description: This article discusses a T-shaped three-coordinate nickel(l) carbonyl complex and the geometric preferences of three-coordinate d9 complexes.
Contributing Partner: UNT College of Arts and Sciences
A Masked Two-Coordinate Cobalt (I) Complex That Activates C-F Bonds

A Masked Two-Coordinate Cobalt (I) Complex That Activates C-F Bonds

Date: July 19, 2011
Creator: Dugan, Thomas R.; Sun, Xianru; Rybak-Akimova, Elena V.; Olatunji-Ojo, Olayinka; Cundari, Thomas R., 1964- & Holland, Patrick L.
Description: This article discusses a masked two-coordinate cobalt(I) complex that activates C-F bonds.
Contributing Partner: UNT College of Arts and Sciences
Selectivity and Mechanism of Hydrogen Atom Transfer by an Isolable Imidoiron (III) Complex

Selectivity and Mechanism of Hydrogen Atom Transfer by an Isolable Imidoiron (III) Complex

Date: May 12, 2011
Creator: Cowley, Ryan E.; Eckert, Nathan A.; Vaddadi, Sridhar; Figg, Travis M.; Cundari, Thomas R., 1964- & Holland, Patrick L.
Description: This article discusses a mechanistic study of hydrogen atom transfer by an isolable iron (III) imido complex, LᴹᵉFeNAd (Lᴹᵉ = bulky β-diketiminate ligand, 2,4-bis(2,6-diisopropylphenylimido)pentyl; Ad = 1-adamantyl).
Contributing Partner: UNT College of Arts and Sciences
Three-Coordinate Terminal Imidoiron(III) Complexes: Structure, Spectroscopy, and Mechanism of Formation

Three-Coordinate Terminal Imidoiron(III) Complexes: Structure, Spectroscopy, and Mechanism of Formation

Date: 2010
Creator: Cowley, Ryan E.; DeYonker, Nathan J.; Eckert, Nathan A.; Cundari, Thomas R., 1964-; DeBeer, Serena 1973-; Bill, E. (Eckhard), 1953- et al.
Description: Article discussing three-coordinate terminal imidoiron(III) complexes and the structure, spectroscopy, and the mechanism of formation.
Contributing Partner: UNT College of Arts and Sciences
Studies of Low-Coordinate Iron Dinitrogen Complexes

Studies of Low-Coordinate Iron Dinitrogen Complexes

Date: December 31, 2005
Creator: Smith, Jeremy M.; Sadique, Azwana R.; Cundari, Thomas R., 1964-; Rodgers, Kenton R.; Lukat-Rodgers, Gudrun; Lachicotte, Rene J. et al.
Description: This article discusses low-coordinate iron dinitrogen complexes. Understanding the interaction of N₂ with iron is relevant to the iron catalyst used in the Haber process and to possible roles of the FeMoco active site of nitrogenase.
Contributing Partner: UNT College of Arts and Sciences
Stepwise Reduction of Dinitrogen Bond Order by a Low-Coordinate Iron Complex

Stepwise Reduction of Dinitrogen Bond Order by a Low-Coordinate Iron Complex

Date: August 24, 2001
Creator: Smith, Jeremy M.; Lachicotte, Rene J.; Pittard, Karl A.; Cundari, Thomas R., 1964-; Lukat-Rodgers, Gudrun; Rodgers, Kenton R. et al.
Description: This article discusses stepwise reduction of dinitrogen bond order by a low-coordinate iron complex.
Contributing Partner: UNT College of Arts and Sciences
Cobalt-Dinitrogen Complexes with Weakened N-N Bonds

Cobalt-Dinitrogen Complexes with Weakened N-N Bonds

Date: June 19, 2009
Creator: Ding, Keying; Pierpont, Aaron W.; Brennessel, William W.; Lukat-Rodgers, Gudrun; Rodgers, Kenton R.; Cundari, Thomas R., 1964- et al.
Description: Article discussing research on cobalt-dinitrogen complexes with weakened N-N bonds.
Contributing Partner: UNT College of Arts and Sciences
Reversible Beta-Hydrogen Elimination of Three-Coordinate Iron(II) Alkyl Complexes: Mechanistic and Thermodynamic Studies

Reversible Beta-Hydrogen Elimination of Three-Coordinate Iron(II) Alkyl Complexes: Mechanistic and Thermodynamic Studies

Date: October 1, 2004
Creator: Vela, Javier; Vaddadi, Sridhar; Cundari, Thomas R., 1964-; Smith, Jeremy M.; Gregory, Elizabeth A.; Lachicotte, Rene J. et al.
Description: Article discussing mechanistic and thermodynamic studies and reversible beta-hydrogen elimination of three-coordinate iron(II) alkyl complexes.
Contributing Partner: UNT College of Arts and Sciences
The Reactivity Patterns of Low-Coordinate Iron-Hydride Complexes

The Reactivity Patterns of Low-Coordinate Iron-Hydride Complexes

Date: April 30, 2008
Creator: Yu, Ying; Sadique, Azwana R.; Smith, Jeremy M.; Dugan, Thomas R.; Cowley, Ryan E.; Brennessel, William W. et al.
Description: This article discusses the reactivity patterns of low-coordinate iron-hydride complexes. The authors report a survey of the reactivity of the first isolable iron-hydride complexes with a coordiination number less than 5.
Contributing Partner: UNT College of Arts and Sciences