Abstract
Phospholes are formally members of the family of 5-membered aromatic heterocycles that includes pyrrole, thiophene and furan. However, phosphole chemistry is quite distinct from that of these well-known heterocycles and what is known about the ring system suggests that it possess relatively little aromatic character. This is associated with the fact that phosphorus retains its normal pyramidal shape, which makes difficult the necessary interaction of the phosphorus lone electron pair with the ring p-system. However, very recent theoretical calculations suggest that if phosphorus were planar the ring could approach thiophene in its degree of aromaticity. We have proceeded to synthesize phospholes with very large P-substituents with the aim of causing flattening of the pyramid so as to test the prediction of an increase in aromatic character. Molecular structures determined by X-ray diffraction analysis indeed revealed a marked flattening of the phosphorus pyramid, along with significant modifications of bond lengths in the expected direction for increased electron delocalization. Furthermore, the ring was found in one compound to undergo electrophilic substitution under mild conditions, and is the first phosphole known to possess this typical property of an aromatic system.
Biography (see Heteroatom Chemistry, Vol. 7, Number 5, 1996)
Louis D. Quin was born in Charleston SC, March 5, 1928. He received his B. S. degree from The Citadel in 1947. He then went on to earn his M. A. degree from the University of North Carolina in 1949 and his Ph.D. from the University of North Carolina, 1952.
Professional Positions
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1949-50 |
Research Chemist, American Cyanamid Co., Stanford, CT, |
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1952-54, 56 |
Research Project Leader, Westvaco Chemical, Division, FMC Corp., Charleston, WV, |
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1954-56 |
Active Duty, US Army Chemical Corps, |
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1956-57 |
Research Associate, Lecturer, Duke University, |
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1957-63 |
Assistant Professor, Duke University, |
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1963-67 |
Associate Professor, Duke University, |
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1967-81 |
Professor, Duke University, |
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1965-70 |
Director of Graduate Studies in Chemistry, Duke University |
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1970-76 |
Chairman, Department of Chemistry, Duke University |
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1981- |
James B. Duke Professor of Chem., Duke University |
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1986 |
James B. Duke Professor Emeritus |
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1986-95 |
Head, Dept. of Chemistry, U of Mass, Amherst |
Appointments on Leave
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1963-64 |
Ford Foundation Fellow, Woods hole |
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1970 |
Visiting Professor, Queen Mary College, London |
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1985 |
Visiting Professor, UNC-CH |
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1992 |
Visiting Professor, U of East Anglia, Norwich |
Editorial positions
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Boards of Editors of: |
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Phosphorus, |
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Phosphorus and Sulfur, |
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Phosphorus, Sulfur and Silicon, and |
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Heteroatom Chemisty. |