Geometries that confer unusual spin and oxidation states to first row metals

Abstract

Stereochem. and electronic structure phenomena of the first row transition ions are central issues in coordination chem. These properties are strongly coupled, and the exptl. detn. of one often intimates a great deal about the other. Our group has an ongoing interest in using ligand design and the methods of inorg. synthesis to prep. transition metal complexes that have unusual spin and oxidn. states. For example, we have been able to prep. examples of pseudotetrahedral Fe(II), Fe(III), and Fe(IV) complexes in which the iron center in each complex is low spin. Likewise, we have reported examples of pseudotetrahedral Co(II) and Co(III) complexes that populated low spin ground states. In this talk I will discuss new data for these types of systems, and I will also discuss ligands and complexes that have been receiving our lab's attention more recently. For instance, we have been able to prep. a family of dicopper complexes whose copper centers are pseudotetrahedral that can reversibly access the oxidn. states Cu(I)Cu(I), Cu(1.5)Cu(1.5), and Cu(II)Cu(II) with minimal changes to their overall structural topologies, but large changes to their Cu-Cu distances and their Cu-X-Cu angles (where X is a bridging ligand) as a function of oxidn. state. By manipulating the auxiliary ligands of these dicopper systems, their geometric and electronic properties can be perturbed in a fascinating way.

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