title: Accurate calculation of zero-field splittings of (bio)inorganic complexes: application to an FeNO7 (S = 3/2) compound.
abstract: Iron nitrosyl complexes with {FeNO}7 (S = 3/2) configuration have a complex electronic structure and display remarkable but not fully understood spectroscopic properties. In particular, {FeNO}7 (S = 3/2) complexes have very large zero-field splittings (ZFSs), which arise from strong spin-orbit coupling, a relativistic effect. The accurate prediction and microscopic interpretation of ZFSs in transition metal complexes can aid in the interpretation of a vast amount of spectroscopic (e.g., Mössbauer and electron paramagnetic resonance) and other experimental (e.g., magnetic susceptibility) data. We report the accurate calculation of the sign and magnitude of ZFSs for a set of representative diatomic molecules based on a combined spin density functional theory and perturbation theory (SDFT-PT) methodology. In addition, we apply the SDFT-PT methodology to accurately calculate the magnitude and sign of the ZFS parameters of an {FeNO}7 (S = 3/2) complex and to interpret its spectrocopic data. We find that the principal component Dzz of the ZFS tensor is very closely oriented along the Fe-N(O) bond, indicating that nitric oxide dominates the very intricate electronic structure of the {FeNO}7 (S = 3/2) compound. We find a direct correlation between electronic delocalization along the Fe-N(O) bond, which is due to pi-bonding, and the large ZFS.
authors.affiliation: Theoretical and Computational Biomolecular Physics Group, Department of Physics, Purdue University, West Lafayette, Indiana 47907-2036, USA.
authors.forename: Fredy
authors.initials: F
authors.lastname: Aquino
authors.forename: Jorge H
authors.initials: JH
authors.lastname: Rodriguez
mesh_terms: D000465:Algorithms; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D058085:Iron Compounds / Q000737:chemistry*; D008280:Magnetics; D008958:Models, Molecular; D008968:Molecular Conformation; D009589:Nitrogen Oxides / Q000737:chemistry*; D011789:Quantum Theory; D015203:Reproducibility of Results; D013455:Sulfur / Q000737:chemistry
chemical_list: D058085:Iron Compounds; D009589:Nitrogen Oxides; D013455:Sulfur