Ligand dependence of binding to three-coordinate Fe(II) complexes.

A series of three- and four-coordinate iron(II) complexes with nitrogen, chlorine, oxygen, and sulfur ligands is presented. The electronic variation is explored by measuring the association constant of the neutral ligands and the reduction potential of the iron(II) complexes. Varying the neutral ligand gives large changes in K(eq), which decrease in the order CN(t)Bu > pyridine >2-picoline > DMF > MeCN > THF > PPh(3).

Preparation and crystal structure of a rhenium analogue of the cationic renal agent, tc-99m diaminocyclohexane.

We report here a chemical study on a Re analogue of one of the few cationic Tc-99m tracers previously investigated as an agent for effective renal plasma flow (ERPF) measurement. Cationic Tc-99m tracers have the potential for overcoming problems associated with common anionic Tc-99m tracers in patients who have developed a uremic state. The Tc-99m-DACH tracer, prepared from 1,2-diaminocyclohexane (1,2-DACH), is the only cationic renal agent tested in humans and has seven possible isomers.

Quantitative geometric descriptions of the belt iron atoms of the iron-molybdenum cofactor of nitrogenase and synthetic iron(II) model complexes.

Six of the seven iron atoms in the iron-molybdenum cofactor of nitrogenase display an unusual geometry, which is distorted from the tetrahedral geometry that is most common in iron-sulfur clusters. This distortion pulls the iron along one C3 axis of the tetrahedron toward a trigonal pyramid. The trigonal pyramidal coordination geometry is rare in four-coordinate transition metal complexes.

Macrocyclic Binucleating β-Diketiminate Ligands and their Lithium, Aluminum, and Zinc Complexes.

The incorporation of rigid aromatic linkers into β-diketiminate ligands creates a binucleating scaffold that holds two metals near each other. This paper discloses the synthesis, characterization, and reactivity of mBin(2-), which has a meta-substituted xylylene spacer, and pBin(2-), which has a para-substituted xylylene spacer. Lithium, aluminum, and zinc complexes of each ligand are isolated, and in some cases are characterized by X-ray crystallography.