faculty

Professor of Chemistry
Ph.D., Yale University

Organometallic Chemistry


Phone: (734) 764-8487     
E-mail: ajashe@umich.edu

Aromatic heterocyclic chemistry has been prolifically investigated for over a century. However, most of the known heteroaromatics involve only a few elements (C, O, N and S). Our group has expanded this field by the preparation of new heteroaromatics with unusual heteroatoms (B, P, As, etc.). This work involves challenging syntheses, while the study of these molecules focuses on fundamental questions of chemical bonding.

This heterocyclic aromatic chemistry has been applied to the preparation of new catalysts for olefin polymerization. Borata-benzenes, the boron analogs of benzene, are negatively charged like cyclopentadienide (Cp). It has been found that boratabenzenes can be substituted for Cp in metallocene catalysts with undiminished activity. However, since boron interacts strongly with its exocyclic substituents, electron density and consequent reactivity at the metal center can be modulated in a unique manner not available using Cp ligands using the rationale we have recently developed a series of novel catalysts for polymerization of ethylene and propylene. Our best catalysts exceed the activity of widely used industrial catalysts.

AWARDS

• Research Fellow, Alfred P. Sloan Foundation

REPRESENTATIVE PUBLICATIONS

1. A. J. Ashe, III; X. Fang; A. Hokky; J. W. Kampf, Organometallics , 2004, 23, 2197, ´The C s -Symmetric Aminoboranediyl Bridged Zirconocene: Its Synthesis, Structure, and Behavior as an Olefin Polymerization Catalyst."
2. A. J. Ashe, III; Z. Bajko; X. Fang ; J. W. Kampf; H. Yang , Phosphorus, Sulfur, and Silicon and Related Elements, 2004 , 179, 711, " New Heteroaromatic pi-Ligands Containing Boron."
3. J. Chen; X. Fang; Z. Bajko ;J. W. Kampf; A. J. Ashe, III, Organometallics , 2004 , 23,5088, "A Boron Analogue of Furan.   The Syntheses and Coordination Chemistry of 2-Substituted-1,2-Oxaborolides."
4. J. Pan ; J. W. Kampf; A. J. Ashe, III, Organometallics, 2004, 23, 5626, "1,2-Azaboratabenzene: A Heterocyclic pi-Ligand with an adjustable Basicity at Nitrogen."
5. H. Yang; X. Fang; J. W. Kampf, A. J. Ashe, III, Polydedron, 2005 , 24, 1280, "Bridged 1,2-azaborolyl zirconium complexes: Heterocyclic analogs of the ansa-ziroconcene olefin polymerization catalysts."
6. J. Pan ; J. W. Kampf; A. J. Ashe, III, 2006 , 25, 197, " switchable Haptotropic Migrations of Tricarbonylchromium Complexes of 1,2-Dihydro-2-phenyl-1,2-azaborine."