Inorganic

Daniel Mindiola, Indiana Univ.; Inorganic Seminar

Tue, 2012-11-27 16:00
Speaker: 

Daniel Mindiola, Indiana University

 

Titanium Alkylidynes. C-H Bond Activation and Beyond

 

Location: 

Lynch Lecture Hall

MacDiarmid Medal Lecture - Richard Schrock

Wed, 2012-11-28 16:00
Speaker: 

Richard R. Schrock, MIT

Location: 

Carolyn Hoff Lynch Lecture Hall

2012 Alan G. MacDiarmid Medal Lecture

 

Molybdenum and Tungsten Catalysts for Selective Olefin Metathesis Reactions

Knowledge by the Slice

Fri, 2012-10-26 12:00 - 13:00
Speaker: 

Eric J. Schelter

Chemistry Department

 

Title: Sustainability, Renewable Energy and Rare Earth Elements

Location: 

Houston Hall, Golkin Room
3417 Spruce Street

 

What makes an insightful, educational, lunch-time faculty lecture series even more appetizing? Pizza, of course! This semester, the School of Arts and Sciences is serving up a new batch of experts. So sit back, relax and enjoy a unique perspective on some of today’s most exciting research areas. And, most importantly, have a slice on us.

 

For more information, click  here.

Muralee Murugesu; Inorganic Seminar

Tue, 2012-10-23 12:00 - 13:00

Location: Carolyn Hoff Lynch Lecture Hall

Suzanne Blum, UC Irvine; Inorganic Seminar

Tue, 2012-10-09 12:00 - 13:00

Location: Carolyn Hoff Lynch Lecture Hall

YuHuang Wang, U of Maryland; Inorganic Seminar

Tue, 2012-10-02 12:00 - 13:30

Location: Carolyn Hoff Lynch Room

Bradford B. Wayland

Photo: 
First Name: 
Bradford B.
Last Name: 
Wayland
Official Title: 
Emeritus Professor of Chemistry

Inorganic Chemistry

Contact Information
Office Location: 
Senior Faculty Suite
Email: 
wayland@sas.upenn.edu
Research Interests: 

Metallo-radical and organo-metal substrate reactions are used in both obtaining living radical polymerization for application in block copoymer materials and energy relevant small molecule organometallic transformations.

Our NSF supported polymer program spans areas from transition metal catalyst development and block co-polymer synthesis to materials applications of nano-structured polymer arrays in membranes, sensors, and microelectronic devices. The reactivity of metal-centered radical species and organometallic derivatives are exploited in the control of radical polymerization by catalytic chain transfer and living radical polymerization. Organo-cobalt porphyrin complexes have recently been observed to mediate a highly precise living radical polymerization of acrylate monomers to form low polydispersity homopolymers and block co-polymers. This new approach to obtaining living radical polymerization occurs by a degenerative transfer pathway that involves rapid interchange of polymeric radicals in the polymer with polymeric units in the organo-cobalt porphyrin complexes. This pathway to obtain living radical polymerization is a transition metal form of degenerative transfer that we refer to as radical interchange polymerization (RIP). The expanding capabilities of living radical polymerization to provide new classes of materials required to advance issues that have significant technological relevance are exploited through an active collaboration with materials science and engineering .Two of the issues targeted as focal points for this collaboration are 1) membranes for water purification and 2) low dielectric thin films for advanced micro electric devices. New materials design strategies are determined for each of the central topics along with the requisite approaches for polymer synthesis, morphology, and property evaluation.

The DOE supported energy related research interests are centered on developing new strategies to accomplish thermodynamically and or kinetically challenging reactions such as methane activation and carbon monoxide reductive coupling and hydrogenation. Ligands are designed to achieve high selectivity through steric and electronic constraints on forming the transition states for substrate reactions .The primary focus is on group nine (Co, Rh, Ir) metal complexes where the importance of metallo-radicals is a recurring theme. Metallo-porphyrins, chlorophylls, and related macrocycles are prominent thermal and photocatalysts in biological systems and emerging as important catalyst materials for chemical manufacturing processes. The unique unique chemical and physical properties of metallo-porphyrins and macrocyclic complexes are used in producing thermal and photocatalytic cycles for small molecule reactions. Several important examples include hydrogenation of CO and CO2, activation of methane, oxidation of alkenes, photoreductions and alkene polymerization. Tethered diporphyrin ligands have been designed and synthesized that are used in forming bimetalloradical complexes of Rh(II). Bimetalloradicals provide preorganization of transition states that involve two metalloradicals and give rapid highly selective substrate reactions. Structural, kinetic-mechanistic, thermodynamic, and reactivity studies are used in characterizing intermediates, anticipating new types of reactions, and guiding strategies to produce selective catalyst materials.

Other Affiliations: 

Temple University, Department of Chemistry

Patrick J. Walsh

Photo: 
First Name: 
Patrick J.
Last Name: 
Walsh
Official Title: 
Professor of Chemistry

Inorganic Chemistry, Organic Chemistry, Chemical Catalysis

Contact Information
Office Location: 
3001 IAST
Email: 
pwalsh@sas.upenn.edu
Phone: 
(215) 573-2875
Fax: 
(215) 573-6743
Admin Support: 
Education: 
  • Advisor Prof. K. Barry Sharpless
  • 1986 B.A. in Chemistry, University of California, San Diego
  • 1991 Ph.D in Chemistry, University of California, Berkeley
  • 1991-1994 NSF Postdoctoral Fellow Postdoctoral, The Scripps Research Institute
Research Interests: 

Research in the Walsh group merges the fields of catalysis and organic and inorganic synthesis with the goal of achieving new catalytic asymmetric transformations for the synthesis of chiral building blocks. The transformations we have chosen to study are asymmetric C-C and C-O bond forming reactions, because construction of these bonds lies at the very heart of organic synthesis. We are also interested in the development of tandem reactions that combine several steps in a single reaction vessel. By introducing tandem reactions, we can increase synthetic efficiency while reducing the number of purification steps necessary. 

 

Shown below are examples of tandem reactions developed in the Walsh group:

 

We are also interested in reaction mechanisms, which gives us the opportunity to synthesize some interesting catalysts. Shibasaki's M3(THF)n(BINOLate)3Ln (Ln = lanthanide, M = Li, Na, K) catalyst are among the most efficient known in asymmetric catalysis. We have studied the structure and reactivity of these amazing catalysts, one of which is shown below.4-6 

We are also interested in structural organozinc chemistry. The first example of zinc coordinated to C-C double bond was recently reported from our group.7 

In 2006 the Walsh group crystallographically characterized about 40 compounds, most of which contained metals.

Larry G. Sneddon

Photo: 
First Name: 
Larry G.
Last Name: 
Sneddon
Official Title: 
Emeritus Professor of Chemistry

Inorganic, Energy and Materials Chemistry

Contact Information
Office Location: 
452 Chem ’73
Email: 
lsneddon@sas.upenn.edu
Phone: 
(215) 898-8632
Admin Support: 
Education: 
  • B.S. Centenary College of Louisiana (1967)
  • Ph.D. Indiana University (1971)
  • Postdoctoral Fellow, University of Virginia (1971-73)
  • Postdoctoral Fellow, Massachusetts Institute of Technology (1973-74)
Research Interests: 

 

Our research in inorganic chemistry, energy-storage and materials science includes synthetic studies in main-group, transition metal and materials chemistry along with physical and structural investigations of molecular, polymeric, and solid-state materials. Brief overviews of ongoing projects are presented in the following sections.

 

Alternative Energy Carriers: New Chemical Methods for Hydrogen Storage

 

The development of efficient methods for hydrogen storage is a major hurdle that must be overcome to enable the use of hydrogen as an alternative energy carrier. We are exploring the use of chemical hydrides such as ammonia borane and ammonia triborane to store and deliver large amounts of hydrogen through dehydrogenation and/or hydrolysis reactions. As depicted in the example in Figure 1, we have shown that the rate and the extent of hydrogen release from these amineboranes can be significantly increased through the use of metal catalysts, ionic liquids and/or chemical additives. We are continuing to investigate both new methods for the controlled hydrogen release from amineboranes and the development of energy-efficient methods for their regeneration from spent-fuel products.

 

Figure 1. Rhodium catalyzed hydrolysis of ammonia triborane

 

Chemical Precursors to Ultra High Temperature Aerospace Materials

The production of complex structural and electronic materials in useable forms is one of the most challenging problems of modern solid-state chemistry and materials science. Our research in this area is focused on the design, syntheses and applications of new processible molecular and/or polymeric precursors to advanced carbide, nitride and boride ceramics that allow the formation of these technologically important materials in forms that cannot be produced with conventional methods. We are especially interested in ultra high temperature materials, such as HfB2 and ZrB2 based composites, that are potentially important in hypersonic (i.e. flying faster than 5 times the speed of sound) aerospace vehicles (Figure 2). A second part of the project is focused on the formation and properties of micro- and nanostructured ceramics, including fibers, tubes and porous materials.

 

Figure 2. New chemical precursor systems for ultra high temperature hafnium-ceramics that were developed at Penn

 

Transition Metal-Promoted Reactions of Inorganic Compounds

We are developing new general, metal-catalyzed methodologies that enable the systematic, high-yield syntheses of important polyborane compounds and materials. Our goals are both to discover new types of catalytic reactions and to develop an understanding of their fundamental reaction mechanisms and controlling factors.

 

Figure 3. (Left) Metal-catalyzed synthesis of the poly(norbornenyldecaborane) polymer; and (Right) The crystallographically determined structure of a new dendritic decaborane (you can manipulate this molecule online at

 

Ionic Liquid Promoted Reactions

 

Ionic liquids have properties that make them attractive solvents for synthesis, including: negligible vapor pressures, thermal stability to elevated temperatures; the ability to dissolve a range of compounds, salts and gases, immiscibility with many hydrocarbons and/or water thus enabling two-phase reaction systems, weakly-coordinating anions and cations that provide a polar, inert reaction medium, and the ability to stabilize polar intermediates and/or transition states. While ionic liquids have been widely employed for organic synthesis, our recent work showing that decaborane olefin-hydroboration and alkyne-insertion reactions proceed in biphasic ionic-liquid/hydrocarbon solvents without the need of the catalysts required in conventional solvents, was the first demonstration of the unique activating effects of ionic liquids for polyborane syntheses. We are continuing to explore the scope of ionic liquid mediated polyborane reactions along with experimental and computational studies of the mechanisms by which these reactions occur.

 

Inorganometallic Chemistry

Because of the unusual ranges of their accessible charges and coordination geometries, polyboranes can function as versatile ligands that can stabilize transition metals in a much wider array of environments than their organic counterparts, such as the cyclopentadienide anion. We are using integrated synthetic, structural (NMR and X-ray crystallography), electrochemical, and computational (DFT/GIAO) investigations to elucidate the nature of polyborane-metal bonding. The unique properties of metallapolyborane complexes are also being exploited to design new metallocene-like complexes with chemical, optical and/or bioactivity properties of importance to solid-state and/or anticancer applications. 

 

 

Figure 4. (Left) Comparisons of the bonding modes of the cyclopentadienyl and tricarbadecaboranyl ligands; (Right) The crystallographically determined structures of new maganatricarbadecaboranyl complexes illustrating a cage-slippage reaction analogous to a cyclopentadienyl ring-slippage process

Eric J. Schelter

Photo: 
First Name: 
Eric J.
Last Name: 
Schelter
Official Title: 
Associate Professor of Chemistry

Inorganic and Materials Chemistry

Contact Information
Office Location: 
3003 IAST
Email: 
schelter@sas.upenn.edu
Phone: 
(215) 898-8633
Fax: 
(215) 573-6743
Twitter: 
@SchelterGroup
Admin Support: 
Education: 
  • B.S. Michigan Technological University (1999)
  • Ph.D. Texas A&M University, Advisor: Kim R. Dunbar (2004)
  • Glenn T. Seaborg Postdoctoral Fellow, Los Alamos National Laboratory (2004-2005)
  • Director's Postdoctoral Fellow, Los Alamos National Laboratory (2006)
  • Frederick Reines Postdoctoral Fellow in Experimental Sciences, Los Alamos National Laboratory (2006-2009)
Research Interests: 

 

Projects in the Schelter Group involve inert atmosphere/Schlenk line synthesis of inorganic and organometallic complexes. Rigorous characterization of new compounds is achieved through X-ray crystallography, NMR, FTIR, and UV-Visible absorption spectroscopies, electrochemistry and magnetic susceptibility studies. Current projects are focused on the chemistries and electronic structure effects of the lanthanides, uranium and main group elements

Advanced Rare Earths Separations Chemistry

The rare earth elements: La-Lu, Y and Sc are used in critical renewable energy applications including wind turbine generators and hybrid electric vehicle batteries. These modern applications require pure rare earth elements that must be separated from their composite mineral sources. The Peoples Republic of China currently holds ~97% of the international rare earths market comprising nearly all aspects of the (environmentally taxing) supply chain. To develop other sources of rare earths and reduce the environmental impact of their isolation, there is a clear need for new separations chemistry that reduces the cost of industrial-scale rare earths separations. This project seeks to develop a totally new extractant strategy by harnessing the physicochemical distinctiveness of certain high-value rare earths. New designer rare earth extractants will enable selective separations chemistry for these technologically critical elements.

 

Capturing Heavy-Fermion Type Electron Correlations in Molecular Complexes

The intermetallic heavy-fermion materials, comprising intermediate valence f-elements such as cerium, are characterized by exotic emergent phenomena including unconventional superconductivity. Recent results on these materials suggest a common energy scale for the emergence of the superconducting state, dependent on the local magnetic interaction of f-moments with conduction electrons. Local electron correlations are also believed to underpin the high Tc superconductivity of other families of materials. Parallel studies in molecular chemistry have begun to show inorganic and organometallic complexes are capable of exhibiting the same type of mixed-valency and correlations found in the heavy-fermion materials.

This project will generalize the requirements for emergence of Kondo-like phenomena in magnetically-dilute molecular complexes. New materials will be synthesized from fundamental units of electron correlation to three-dimensional molecular phases.

 

 

 

Exploring the Inverse Trans Influence in the Chemistry of Uranium

Antithetical to the trans influence in transition metal chemistry, which results in a weakening of metal-ligand bonds trans to strongly-bound groups, is the inverse trans influence in the chemistry of the actinides. Semi-core p-orbital mixing with valence d- or f-orbitals gives rise to the influence, however, the presence of both orbital types in the actinide valence shell precludes its simple description. The large thermodynamic stability of the ubiquitous linear, trans-dioxo uranyl cation, UO22+ is one important consequence of this influence.

This project will develop new complexes in varying geometries and coordination environments to systematically study the inverse trans influence in the structural chemistry of uranium. These results will have direct relevance to the bio-remediation of actinide contaminated ground waters, for which the thermodynamic driving force of the influence plays an important role.

Department of Chemistry

231 S. 34 Street, Philadelphia, PA 19104-6323

215.898.8317 voice | 215.573.2112 fax | web@chem.upenn.edu

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