A Chemist’s Way of Thinking
Monday, February 21, 2011
4:00 p.m. Room 1004 Shelby Hall
(General Audience Lecture)
Generation of (Radical) Cations by Means of Extreme Oxidants
Tuesday, February 22, 2011
12:45 p.m. Room 1093 Shelby Hall
Professor Doctor Konrad Seppelt, Professor of Chemistry at the Free University of Berlin, was born in Leipzig, Germany in September 1944. Konrad studied at the Universities of Hamburg and Heidelberg and received his Diplom from the latter in 1968. Konrad remained at the University of Heidelberg to earn his PhD in 1970 under the direction of Professor Dr. Wolfgang Sundermeyer. Konrad started his independent research career and habilitation at the University of Heidelberg. During that time, he spent one year on sabbatical at UC Berkeley (1974-75) in the Neil Bartlett labs. Konrad was promoted to Associate Professor at the University of Heidelberg in 1980. That year, he moved to the Free University of Berlin where he has remained for the past three decades. Konrad served as Vice President for Research at the Free University of Berlin from 1992 to 1995. He also served twice as Dean.
Konrad has developed a world-leading and internationally lauded program related to fluorine and noble gas chemistry. He has prepared more examples of compounds once thought incapable of existence than perhaps anyone has. His unique synthetic contributions include preparations of CF3OH, SF5OH, CF3NH2, TeF5NH2, SF5OCN, SeF5OCN, SeOF4, and cyclo-C5F5-), as well as the non-fluorine containing species AsCl5, AsOCl3, Br2O3, and Br2O5. He has single-handedly developed the area of fluorine-stabilized sulfur-carbon multiple bonds including the initial syntheses of the following bond types: SF4=CR2, SF3≡CR, O=SF2CR2, and SF2=CR2. Konrad has pioneered the chemistry of extremely electron-withdrawing substituent groups such as -OSeF5 and -OTeF5 and has shown that the later group can be used to stabilize maximum oxidation states. Examples of particular importance include the noble gas compounds Xe(OSeF5)2, Xe(OTeF5)4, XeO(OTeF5)4, and Xe(OTeF5)6. The latter of these species is monomeric and highly colored, properties that reflect the nature of the lone pair electrons on xenon. Careful consideration of color has allowed Konrad to describe a number of interesting species including pentaphenyl bismuth derivatives, Xe2+, Xe4+, XeCl+, Cl4+, and Cl2O2+. The isolation and structural characterization of many of these species have only been possible by working in the superacid system HF/SbF5. Professor Seppelt has also rigorously pursued structural investigations of all nine transition metal hexafluorides and many highly coordinated fluoroanions including SeF62-, TeF7-, ROTeF6-, BrF6-, IF6-, IF8-, IOF6-, XeF7-, XeOF5-, ReOF6-, ReF8-, WF82-, and UF82-, among others. Similarly, he has prepared and characterized many permethylated neutral and anionic main-group and transition metal complexes including Bi(CH3)5, Bi(CH3)6-, Ti(CH3)4, Ti(CH3)5-, Ti2(CH3)9-, Nb(CH3)6-, Ta(CH3)6-, Mo(CH3)6, Mo(CH3)7-, W(CH3)6, and Re(CH3)6. Even with all of the aforementioned research accomplishments, Konrad is probably best known for preparing the first examples of stable bonds between a noble gas and a metal, namely xenon with gold or mercury, including the following cations: AuXe4+, cis-AuXe4+, trans-AuXe2+, trans-AuXe2F+, and HgXe2+. Notably, the first examples involve bonding between a noble gas and a noble metal.
Professor Seppelt is the recipient of several fellowships and prestigious awards. He has been presented with a Karl Winnacker Award, the Prize for Chemistry of the Academy of Sciences of Göttingen, the Wilsmore Fellowship of the University of Melbourne, the ACS Award for Creative Work in Fluorine Chemistry, and the 2001 Wilhelm Klemm Award for Inorganic Chemistry from the German Chemical Society. Konrad has also been honored as a named lecturer at many top universities around the world. He has presented the Eduard Zintl Lecture (Technical University of Darmstadt), J. J. Mosher Lecture (Hebrew University, Jerusalem), Wilhelm Manchot Lecture (Technical University of Munich), A.D. Little Lecture (MIT), E.L. Muetterties and Neil Bartlett Memorial Lectures (UC Berkeley), R. Siedle Lecture (Indiana University), Lee Memorial Lecture (University of Chicago), John C. Bailar, Jr. Lecture (University of Illinois), E. Wiberg Lecture (University of Munich)), and the Roessler Lecture (Cornell University). To date, Konrad has authored nearly 300 journal and review articles related to his extraordinary work in fluorine, noble gas, and other main group element chemistry.