ChemInform Abstract: Variable Photon Energy Photoelectron Spectroscopy on FeCl‐ 4: An Unusual Electronic Structure for High‐Spin d5 Complexes.

Abstract

005ChemInform Abstract The PES spectra obtained for CsFeCl4 over the energy range 25-150 eV show intensity changes in the valence band features which indicate that more metal character is present in the deepest bonding levels. This is inverted compared to the normal electronic structure description of transition-metal complexes. The lack of off-resonance intensity in the deep binding energy satellite indicates that little relaxation occurs upon ionization. A configuration interaction analysis shows that the resonance profiles of the peak intensities at the absorption edge are also consistent with an inverted ground-state bonding scheme with little relaxation occurring upon ionization. Both the inverted bonding scheme and the very small relaxation are reproduced by spin-unrestricted but not by spin-restricted SCF-Xα-SW calculations.

Ferric–Thiolate Bond Dissociation Studied with Electronic Structure Calculations

“…In the calculations for 6 R employing spatially restricted orbitals (ROHF and CASSCF), we observe a typical molecular orbital ordering equivalent to what is usually expected from d 5 metal centers with tetrahedral coordination. 52 The valence orbitals of the sulfur ligand combine into nonbonding MOs belonging approximately to the T 1 irrep in the T d local symmetry around the iron center and into bonding MOs belonging to irreps A 1 , E, and T 2 . The five unpaired electrons of the metal are distributed in e 2 t 2 3 -like orbitals, with contributions of about 5−10% weight from ligand orbitals from irreps E and T 2 .…”