Keith Hollis
Associate Professor
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Contact Information
Office: 407 Coulter Hall
Phone: 662-915-5337
Email: hollis AT olemiss.edu
Educational and Professional Background
B.A., Huntingdon College, 1989
Ph.D., The University of Chicago, 1995
NIH Postdoctoral Fellow, UC Irvine, 1995-1998
Research Interests: Fundamental Catalyst Design and Development: N-heterocyclic carbene Pincer complexes of the transition metals: Synthesis, characterization and application to catalysis of organic transformations of relevance to total synthesis, pharmaceuticals, and polymer synthesis. Carbon-carbon and carbon-nitrogen bond forming reacctions. Nano-materials: Preparation of new nano-materials based on our complexes through templated synthesis.
Use of Perforated Anodized Alumina Membranes as templates for the synthesis of orgnaometallic nano-materials.
Educational interests include innovation in the classroom environment through Internet-based writing-to-learn programs such as Calibrated Peer Review (CPR) and the use of Audience Response Systems (clickers) that underlie question driven instruction. |
Research Summary
Pincer Carbene Synthesis
Our group is focused on developing novel architectures to provide the next privileged ligand. We attack this problem by doing the fundamental chemistry necessary to design, prepare and explore new architectures. Our present project involves the development of a new class of N-heterocyclic carbene (NHC) ligands, a CCC-NHC pincer architecture, which we conceived, designed and developed. To achieve our ligand architecture a new synthetic methodology was developed that is mild, fast and general. As illustrated in the equation below a Zr amide activated all three C-H bonds simultaneously. The Zr complex efficiently transmetallated to Rh in good to excellent yields.
X-ray crystal structures are illustrated in the figure below for a) the asymmetric unit and b) the iodo-bridged dimer of the Rh complex with the butyl groups omitted for clarity.
Current work involves the generalization of this methodology for other ligand structures and different metals. We are also develpoping chiral variants of the pincer carbene architecture.
Nano-Materials/ Nano-Science
Preparation of new nanomaterials based on our complexes through templated synthesis has been accomplished. Use of a standard procedure employing Porous Anodized Alumina Membranes as templates for the synthesis of organometallic nanotubes has been demonstrated. Study of the fundamental nature and control of these materials is underway.
The optical, SEM and TEM images of the nanotubes are presented below. These revealed the hollow nature and existence of nanopores along the main axis of the nanotubes.
Optical Image
SEM images. Arrows indicate nanopores.
TEM Image
For the latest PubMed bibliographic information click on this link:
T. K. Hollis references.
Recent Publications
Joon Cho, T. Keith Hollis,* Theodore R. Helgert An Improved Method for the Synthesis of Zirconium (CCC-N-Heterocyclic Carbene) Pincer Complexes and Applications in Hydroamination, Chemical Communications, 2008, 5001-5003 DOI: 10.1039/b805174g.Andriy Nadtochiy, T. Keith Hollis,* and Igor Ostrovskii* Ferroelectric bimorph cantilever with self-assembled silane layer,” Applied Physics Letters, 2008, 92, 263503.William P. Freeman, Yi Joon Ahn, T. Keith Hollis,* J. Andrew Whitaker, Victor C. Vargas, Ramel J. Rubio, Karen D. Alingog, Eike B. Bauer, Fook S. Tham Isomerization in Bent Phosphametallocenes: Combining Rotational Barriers and the Intramolecular Slip-Inversion-Slip Mechanism to Control Stereo-Conformation, Journal Of Organometallic Chemistry, 2008, 693, 2415-2423, DOI: 10.1016/j.jorganchem.2008.04.021.Bauer, E. B.; Andavan, G. T. S.; Hollis, T. K.; Rubio, R. J.; Cho, J.; Kuchenbeiser, G. R.; Helgert, T. R.; Letko, C. S.; Tham, F. S., "Air- and Water-Stable Catalysts for Hydroamination/Cyclization. Synthesis and Application of CCC-NHC Pincer Complexes of Rh and Ir," Org. Lett., 2008, 10, 1175-1178.Yi Joon Ahn, Ramel J. Rubio, T. Keith Hollis,* Fook S. Tham,
Bruno Donnadieu Slip-Inversion-Slip Mechanism of Phosphametallocene
Isomerization. Spectroscopic Characterization of an 1-Phospholyl Ti
Complex. Synthesis and Structures of Chiral Monophospholyltitanium
Complexes, Organometallics, 2006, 25, 1079-1083.Sathyajith Ravindran, G. T. Senthil Andavan, Chunglin Tsai,
Cengiz S. Ozkan,* and T. Keith Hollis* Perforated Organometallic
(POM) Nanotubes Prepared from a Rh N-Heterocyclic Carbene using a
Porous Anodized Alumina Membrane (PAAM), Chemical
Communications, 2006, 1616.Gurusamy Thangavelu Senthil Andavan, Eike B. Bauer, Christopher
S. Letko, T. Keith Hollis,* Fook S. Tham Synthesis and
Characterization of a Free Phenylene Bis(N-Heterocyclic Carbene) and
its di-Rh complex. Catalytic Activity of the di-Rh and CCC-NHC Rh
Pincer complexes in Intermolecular Hydrosilylation of Alkynes,
Journal of Organometallic Chemistry, 2005, 690,
5938-5947.Ramel J. Rubio, Gurusamy Thangavelu Senthil Andavan , Eike B.
Bauer, T. Keith Hollis,* Joon Cho, Fook S. Tham, Bruno Donnadieu
Toward a General Method for CCC N-Heterocyclic Carbene Pincer
Synthesis: Metallation and Transmetallation Strategies for Concurrent
Activation of Three C-H Bonds, Journal of Organometallic
Chemistry, 2005, 690, 5353-5364.T. Keith Hollis, Yi Joon Ahn, Fook S. Tham "Low-Valent Titanium
Bis(phospholyl) Chemistry: A Configurationally Stable Chiral
Phosphatitanocene," Organometallics 2003, 22, 1432-1436.Li-Sheng Wang, T. Keith Hollis "Demonstration of a
Phosphazirconocene as a Catalyst for the Ring Opening of Epoxides with
TMSCl," Org. Lett. 2003, 5, 2543-2545.Victor C. Vargas, Ramel J. Rubio, T. Keith Hollis, Martha E.
Salcido An Efficient Route to 1,3-Di-N-Imidazolylbenzene. A
Comparison of Monodentate vs. Bidentate Carbenes in Pd Catalyzed Cross
Coupling, Org. Lett. 2003,5, 4847-4849. T. Keith Hollis, Yi Joon Ahn, Fook S. Tham "The First Structural
Characterization and Determination of the Isomerization Activation
Parameters of a Chiral Phosphatitanocene," Chem. Commun.
2002, 2996-2997.T. Keith Hollis, Li-Sheng Wang, Fook Tham "Dynamic Resolution of
a Metallocene: Diastereoselective Assembly of an Early Late
Heterobimetallic Metal Bridged ansa Metallocene Opening a Route to
Parallel Catalyst Synthesis." Journal of the American Chemical
Society, 2000, 122, 11737-11738. |
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