X-ray absorption Fe−K edge data on ferrous and ferric model complexes have been studied to establish a detailed understanding of the 1s → 3d pre-edge feature and its sensitivity to the electronic structure of the iron site. The energy position and splitting, and intensity distribution, of the pre-edge feature were found to vary systematically with spin state, oxidation state, geometry, and bridging ligation (for binuclear complexes). A methodology for interpreting the energy splitting and intensity distribution of the 1s → 3d pre-edge features was developed for high-spin ferrous and ferric complexes in octahedral, tetrahedral, and square pyramidal environments and low-spin ferrous and ferric complexes in octahedral environments. In each case, the allowable many-electron excited states were determined using ligand field theory. The energies of the excited states were calculated and compared to the energy splitting in the 1s → 3d pre-edge features. The relative intensities of electric quadrupole transitions...

A Multiplet Analysis of Fe K-Edge 1s → 3d Pre-Edge Features of Iron Complexes

The structure and mechanism of iron-hydrogenases

Groundworks for an evolutionary biochemistry: The iron-sulphur world

Synthetic Analogues and Reaction Systems Relevant to the Molybdenum and Tungsten Oxotransferases

Thermodynamic, electrochemical and quantum chemical investigation of some Schiff bases as corrosion inhibitors for mild steel in hydrochloric acid solutions

A series of dioxo-Mo(VI) Schiff base complexes of the type MoO 2 (R-L)(solv) has been prepared: L=2-(salicylideneamino)-phenolate(2-) (sap) or 2-(salicylideneamino)benzenethiolato(2-) (ssp); solv=solvent. Salicylidene ring substituents R were selected to promote solubility and crystallinity. The unsubstituted complexes MoO 2 (sap)(solv) and MoO 2 (ssp)(solv) have been previously reported. The structures of two members of the series were determined

Oxomolybdenum(IV,V,VI) Complexes: Structures, Reactivities, and Criteria of Detection of Binuclear (μ-oxo)molybdenum(V) Products in Oxygen Atom Transfer Systems

Binuclear iron system ferromagnetic in three oxidation states: synthesis, structures, and electronic aspects of molecules with a Fe2(OR)2 bridge unit containing Fe(III,III), Fe(III,II), and Fe(II,II)

Le compose du titre cristallise dans le systeme cubique, groupe d'espace Pa3 et sa structure est affinee jusqu'a R=0,046

Trichlorotetrakis(triethylphosphine)hexathioheptairon (Fe7S6(PEt3)4Cl3): a topological link between the prismatic and cube-octahedral structures of iron-sulfur clusters

The reaction system FeCl{sub 3}:3.15Na(PhNC(O)Me): 1.78Li{sub 2}S in ethanol/methanol (2:1 (V/v)) affords, after the addition of Pr{sub 4}NBr and a 5-day period of reaction and crystallization, the black compound (Pr{sub 4}N){sub 6}Na{sub 4}Fe{sub 18}S{sub 30} in 60-75% yield. When this material is very slowly crystallized from acetontrile/ether, the solvated compound (Pr{sub 4}N){sub 6}Na{sub 4}Fe{sub 18}S{sub 30} {times} 14MeCN is obtained. This compound crystallizes in triclinic space group P{anti 1} with a = 16.286 (8) {angstrom}, b = 16.718 (8) {angstrom}, c = 17.902 (9) {angstrom}, {alpha} = 115.28 (3){degree}, {beta} = 91.07 (4){degree}, {gamma} = 101.64 (4){degree}, and Z = 1. The structure was refined to R = 6.5%. The crystal structure consists of discrete Pr{sub 4}N{sup +} ions and two Na{sup +} ions weakly associated with the cluster (Na{sub 2}Fe{sub 18}S{sub 30}){sup 8{minus}}, which has a remarkable and unprecedented structure. It is constructed by the fusion of 24 nonplanar Fe{sub 2}s{sub 2} rhombs in edge- and corner-sharing modes such that there are 20 {mu}{sub 2}-S, 8 {mu}{sub 3}-S, and 2 {mu}{sub 4}-S, every FeS{sub 4} unit is tetrahedral, and the 18 Fe atoms are essentially planar. The result is a cyclic or toroidal structure, of lateral dimensions 13.3 {times}more » 16.0 {angstrom} and a maximum thickness of ca. 3.3 {angstrom}, in which there are no terminal ligands. Two Na{sup +} ions are bound to interior sulfur atoms of the cluster, whose framework can be considered to arise from the sequential connection of known Fe{sub 3}S{sub 4} and Fe{sub 6}S{sub 9} cluster cores. Alternative conceptions of cluster buildup in terms of shared Fe{sub 2}S{sub 2} rhombs and FeS{sub 4} tetrahedra are presented and illustrated.« less

B. S. Snyder

Papers

Oxomolybdenum(IV,V,VI) Complexes: Structures, Reactivities, and Criteria of Detection of Binuclear (μ-oxo)molybdenum(V) Products in Oxygen Atom Transfer Systems

Binuclear iron system ferromagnetic in three oxidation states: synthesis, structures, and electronic aspects of molecules with a Fe2(OR)2 bridge unit containing Fe(III,III), Fe(III,II), and Fe(II,II)

Trichlorotetrakis(triethylphosphine)hexathioheptairon (Fe7S6(PEt3)4Cl3): a topological link between the prismatic and cube-octahedral structures of iron-sulfur clusters

On the molecular solid-state boundary. A cyclic iron-sulfur cluster of nuclearity eighteen: synthesis, structure, and properties

A binuclear mixed-valence ferromagnetic iron system with an S = 9/2 ground state and valence trapped and detrapped states