CENTC researchers find gases react inside single crystals

A newly synthesized family of molecular single crystals has two remarkable capabilities, reported in this week's Nature by CENTC researchers Prof. Maurice Brookhart (Univ. Of North Carolina) and graduate student Zheng Huang (now a post-doctoral fellow at Univ. Of Illinois, Urbana-Champaign). Members of the molecular family can exchange small gaseous ligands for others, while retaining their integrity as single crystals; and some of the family members can act as selective catalysts for the hydrogenation of ethylene gas.
Maurice Brookhart and colleagues synthesized an organometallic compound, [Ir]-N₂, in which a reactive iridium atom, supported by an organic 'pincer' ligand, binds a nitrogen molecule. Crystallizing this compound from a toluene solution yields single crystals, in which the [Ir]-N₂ molecules are stacked around channels containing toluene molecules.

Exposing the [Ir]-N₂ crystals to other small-molecule gases, such as carbon monoxide, ammonia or ethylene, results in solid-state transformations to analogous compounds in which each of these gases replaces nitrogen. The authors show that these transformations take place by direct exchange reactions inside the intact crystals, rather than by ligand loss followed by uptake. The gaseous ligands evidently enter the crystals via the toluene-containing channels, which exclude entry by all but the smallest molecules.

Three of the compounds also function as hydrogenation catalysts for ethylene and propylene, with a strong selectivity for the smaller gas when reactions are prevented from occurring at or near the crystal surfaces. This appears to be the first demonstration of a selective catalytic reaction occurring inside an organometallic crystal.

Read the full article: Huang, Z.; White, P. S.; Brookhart, M. “Ligand Exchanges and Selective Catalytic Hydrogenation in Molecular Single Crystals”, Nature, 2010, 465, 598-601.
DOI: http://dx.doi.org/10.1038/nature09085

2010 CENTC Summer School Accepting Applications

CENTC is sponsoring a summer school to be held July 19-22, 2010 at the University of Washington in Seattle. The four-day in-residence summer school program will emphasize purposes, techniques, challenges and career opportunities in catalysis as the 21st century progresses. Advanced Ph.D. students, post-doctoral fellows, early-career researchers and faculty members from primarily undergraduate institutions who are interested in deepening their understanding of organometallic catalysis are encouraged to apply.

To learn more, visit the Summer School website.

Diverse Backgrounds, Common Goals Social at ACS National Meeting

CENTC, Procter & Gamble, Dow and UOP are co-hosting the second Diverse Backgrounds, Common Goals event at the National ACS meeting in San Francisco on Monday, March 22, 2010 from 5:30 - 7:30 pm. This open social event is being organized by CENTC and American Competitiveness in Chemistry postdoctoral fellow, Dr. Takiya Ahmed, with the goals of fostering integration and partnerships among national science organizations interested in diversity and between those organizations and industry, and to provide networking opportunities for undergraduate, graduate, and postdoctoral students.

Stop by the Moscone Convention Center room 2011 any time between 5:30 pm - 7:30 pm on Monday, March 23rd for complimentary refreshments and lots of mingling.

CENTC congratulates recent graduates

The Center for Enabling New Technologies through Catalysis extends congratulations to two recent graduates:

Chris Waidmann was a graduate student with Prof. James Mayer at the University of Washington. Chris’ dissertation title is "Investigating Proton Coupled Electron Transfers in Oxovanadium and Dimeric Copper-Oxo Systems: The Importance of Intrinsic Barriers and Reaction Driving Force".

Sabuj Kundu, a graduate student at Rutgers University with Prof. Alan Goldman, wrote his thesis on “Reactions of (PCP)Ir Complexes With Small Molecules”.

Congratulations CENTC graduates!

Three CENTC investigators elected as AAAS Fellows

CENTC investigators R. Thomas Baker (Univ. of Ottawa), William Jones (Univ. of Rochester) and Huimin Zhao (Univ. of Illinois - Urbana-Champaign) have been elected as Fellows of the American Association for the Advancement of Science. AAAS recognizes Fellows for their contributions to science and technology.

Read the press release and full list of elected Fellows.

New AAAS Fellows Baker, Jones and Zhao

New insight into the conversion of methane to ethane by palladium-based catalysts

As part of CENTC's continuing attempts to develop catalytic processes to utilize methane gas as a potential source of fuel and other chemicals, CENTC investigators James Mayer (University of Washington) and Melanie Sanford (University of Michigan) have reported a better understanding of the way certain palladium-based catalysts release methane to form ethane. The studies, conducted collaboratively by the Mayer and Sanford research groups, were reported as a Communication in the Journal of the American Chemical Society (JACS) on October 13, 2009.

Sanford and Mayer investigated the ferrocenium-induced elimination of palladium-bound CH₃ to give ethane in order to determine which of three possible pathways was a likely route for the reaction to take. A series of experiments were carried out that suggested the reaction did not involve methyl radicals and did involve a Pd(IV) intermediate. Further reactions were carried out at low temperature (-80° C) and the Pd(IV) intermediate was observed by nuclear magnetic resonance (NMR) spectroscopy. Additional experiments with other oxidants suggested that Ag⁺ follows a similar mechanism but benzoquinone behaves differently.

The studies conducted by Mayer and Sanford are part of an ongoing project by CENTC researchers to develop catalysts for the direct oxidative dimerization or oligomerization of methane. The overall goal of this project is to address the need to form higher alkanes from methane via processes that do not involve energy-intensive cracking or steam reforming to syngas.

"Oxidatively Induced Reductive Elimination from (^tBu₂bpy)Pd(Me)₂: Palladium(IV) Intermediates in a One-Electron Oxidation Reaction" Michael P. Lanci, Matthew S. Remy, Werner Kaminsky, James M. Mayer and Melanie S. Sanford, J. Am. Chem. Soc., 2009, 131 (43), pp 15618-15620

[DOI: 10.1021/ja905816q]

Read the JACS Communication

Melanie Sanford Named Esquire Magazine's Chemist of the Year

CENTC investigator Melanie Sanford has been named Chemist of the Year in the December 2009 issue of Esquire Magazine. The article (pg. 163) touts Prof. Sanford as "a one-woman special-ops unit called in by chemical and drug companies to break down and put together molecules at her whim." Esquire goes on to describe her National Science Foundation-funded efforts "to convert methane - an abundant natural gas that's usefulness is limited because it's difficult to transport - into a petroleum-like fuel. If she succeeds, she will effectively double the world's fuel supply for pennies."