Multifrequency EPR study of S = 1 vanadium (III) complexes with nitrogen containing ligands

INOR 937

Marcin Brynda, mabrynda@ucdavis.edu1, Bath S. Krishnamoorthy2, Michel Geoffroy2, Guillem Aromi, guillem.aromi@antares.qi.ub.es3, and J. Krzystek, krzystek@magnet.fsu.edu4. (1) Department of Chemistry, University of California, Davis, 1 Shields Ave., Davis, CA 95616, (2) Department of Physical Chemistry, University of Geneva, 30 q. Ernest Ansermet, Geneva, 1211, Switzerland, (3) Departament de Química Inorgànica, Universitat de Barcelona, Diagonal 647, Barcelona, E-08028, Spain, (4) National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310
Vanadium is essential to bacterial enzyme systems that fix nitrogen from the atmosphere and it is believed to interact with proteins in mammalian organisms. We have investigated a series of complexes formed by vanadium(III) with nitrogen containing phenantroline and pyridine ligands. The magnetic properties of these complexes were characterized by bulk magnetic susceptibility/magnetization as well as resonance methods. In the latter case we employed parallel-mode detection of X-band EPR, but primarily high-frequency and -field EPR (HFEPR, frequencies 50 – 700 GHz, fields 0 – 25 T), which was necessary in view of significant zero-field splitting appearing in the ground triplet (S = 1) state. Preliminary interpretation of HFEPR results indicates the following spin Hamiltonian parameters for that state: D ~ +5 cm-1, |E| ~ 0.1 cm-1, g ~ 1.85 (as expected for the 3d2 electronic configuration) which will be compared with results of DFT calculations.
 

Spectroscopy of Inorganic Systems
9:00 AM-11:20 AM, Thursday, August 23, 2007 BCEC -- 211, Oral

Division of Inorganic Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007