大型放射光施設 SPring-8

Speaker : Robert K. SZILAGYI

Language : ENGLISH

Affiliation : Department of Chemistry and Biochemistry, Montana State University

Title : In Search of the Perfect Synchrotron Facility for Multi-Edge X-ray Absorption Spectroscopy; Electronic Structure from XANES and Geometric Structure from EXAFS.

Abstract :
Multi-edge X-ray Absorption Spectroscopy is a powerful approach to obtain direct experimental information about the electronic and geometric structures of transition metal complexes with unoccupied d-orbital manifolds.

X-ray Absorption Near Edge Spectroscopic measurements and molecular orbital-based analysis of pre-edge and rising-edge features can provide information about the orbital contribution and effective nuclear charge of an absorber. These are key electronic structural information to define quantitatively the degree of covalent and ionic interactions involving the absorber. Data obtained in the energy range of hard, tender, and soft X-rays provide metal p, ligand p and metal d for third row main group elements and second row transition metals, and metal d and ligand p for first row transition metals and second row main group elements, respectively.

The multi-edge Extended Absorption Fine Structure analysis has the potential to define atomic positional coordinates for non-crystalline samples with accuracy that is comparable to small molecule crystallography.

The presentation will highlight case studies to demonstrate the power of using multi-edge XAS measurements through examples obtained from the beamlines of Stanford Synchrotron Radiation Lightsource in Menlo Park CA, Advanced Light Source in Berkeley CA, Synchrotron Research Center in Stoughton WI, and the Canadian Light Source in Saskatoon Canada.
Transition metal complexes studied will include biomimetic compounds of FeFe-hydrogenase metalloenzyme, non-innocent Cu and Ni pincer type complexes, pre-catalysts for Pd-based homogeneous organometallic reactions.

Key references:
Rokhsana D., Howells A.E., Dooley D.M., Szilagyi R.K.: Role of the Tyr-Cys Cross-link to the Active Site Properties of Galactose Oxidase Inorganic Chemistry, 2012, 51(6), 3513-3524

Giles L.J., Grigoropoulos A., Szilagyi R.K.: Multi-Edge X-Ray Absorption Spectroscopy Part I: XANES Analysis of a Biomimetic Model of FeFe-Hydrogenase Journal of Physical Chemistry A, 2012, 116(50), 12280-12298

Queen M.S., Towey B.D., Murray K.A., Veldkamp B.S., Byker H.J., Szilagyi R.K.: Electronic Structure of [Ni(II)S4] Complexes from S K-edge X-ray Absorption Spectroscopy Coordination Chemistry Reviews, 2013, 257(2), 564-578

Mossin S., Tran B.L., Adhikari D., Pink M., Heinemann F.W., Sutter J., Szilagyi RK, Meyer K., Mindiola D.J.: A Mononuclear Fe(III) Single Molecule Magnet with a 3/2 <-> 5/2 spin crossover The Journal of American Chemical Society, 2012, 134(33), 13651-13661

担当者 : 新田 清文
Mail : nittak@spring8.or.jp
PHS : 3775