Member, Materials Science Institute

B.A., Rice University, 1987. Ph.D., Rice University, 1991 (W. Edward Billups). Postdoctoral: University of California, Berkeley, 1991-93 (K. Peter C. Vollhardt). Honors and Awards: American Chemical Society, Division of Organic Chemistry Fellowship, 1990-91; NSF Postdoctoral Fellowship, 1991-93; NSF CAREER Award, 1995-1998; US-Israel BSF Ernst D. Bergmann Memorial Award, 1997; Richard A. Bray Faculty Fellow, 1998; Camille Dreyfus Teacher-Scholar, 1998-2003; Alexander von Humboldt Research Fellow, 2000-2001; Thomas F. Herman Faculty Achievement Award for Distinguished Teaching, 2002, University of Oregon Fund for Faculty Members Excellence Award, 2007. At Oregon since 1993.

Research Interests:

The research interests of my group are deeply rooted in the exploration of important non-natural aromatic systems. The group utilizes current synthetic methodology for the preparation of novel organic materials and compounds of theoretical interest. We investigate these compounds by modern physical organic methods in order to determine the important physical and chemical properties of these systems, such as conductivity, non-linear optical activity, through-bond and through-space electronic interactions. Graduate and undergraduate students are actively involved in all aspects of the research, thus acquiring a strong synthetic and theoretical background.

1. Acetylene chemistry.

Carbon-rich materials are currently of extreme interest to researchers in many fields and have become the subject of an increasing number of experimental and theoretical studies due to the recent isolation and characterization of the fullerenes (C60, C70, etc.) in macroscopic quantities. The major focus of our research into these materials is on two overlapping subsets: (a) carbon networks and models, and (b) molecules with a high C:H ratio. Both studies are based on a class of molecules known as dehydrobenzoannulenes (DBAs).

Calculations predict stable, low energy phases of carbon consisting of stacked, planar carbon layers occupied by sp and sp2 states (e.g., 1). The properties of these novel carbon networks are of great relevance in the search for organic conductors, electrochromic display materials, liquid crystals, synthetic ferromagnets, and non-linear optical substances. We have prepared a variety of DBA model compounds (e.g., 2 and 3) for each network in order to compare the chemical and physical properties of the models with those we observe for the corresponding polymeric materials, thus allowing us to probe the monomer/polymer interface. Investigations with modern X-ray and solid-state NMR spectroscopic techniques are an important part in the identification of the extended frameworks.

New synthetic methods developed during the network studies have allowed us to assemble a diverse array of DBA topologies, with nearly 100 macrocycles completed in the past eight years. The structures illustrated below represent some of these molecules. Compounds 4 and 5 represent the first examples of DBAs containing more than two consecutive acetylenic units per side. ‘Wheel’ 6 illustrates a new class of π-extended, fully conjugated fenestranes. We can now prepare structures incorporating transition metal fragments (e.g., 7). Most importantly, the stepwise assembly process used to synthesize our macrocycles allows us to tailor the substituent placement on the aromatic rings, creating for the first time derivatized donor-acceptor structures like 8 for nonlinear optical applications.

2. Heterocycle synthesis.

An offshoot of our annulene chemistry has been the discovery of two unusual cyclization reactions of (2-ethynylphenyl)triazenes (intermediates in annulene preparation) to give either cinnolines (9) or isoindazoles (10) in very good to excellent yields. Depending upon the choice of reaction conditions, the cyclizations can favor either a (pseudo)pericyclic or (pseudo)coarctate mechanistic pathway via zwitterion or carbene intermediates, respectively.

We are exploring the synthetic utility of this class of cyclization reactions to prepare other unusual heterocyclic compounds. In addition, we continue to probe the mechanistic details by both experimental techniques and theoretical (DFT) calculations. (2-Ethynylphenyl)phenyldiazenes (11) and 2-(phenylazo)benzonitriles (12) are two systems currently under investigation.

3. Metalla-aromatic chemistry.

This area of chemistry pushes the frontiers of our understanding of the bonding and reactivity in organometallics as often time systems of this type defy conventional wisdom. The key to our research is the preparation of cyclopropenes containing additional unsaturated moieties and their subsequent reaction with transition-metal reagents to yield novel organometallic complexes.

A metallabenzene (e.g., 13) is a transition-metal analog of benzene in which one methine (CH) is replaced by an isoelectronic MLn fragment, yet the molecule retains "aromatic" physical and chemical properties. Although two dozen or so such structures are known, there was no general route that allowed entry into this class of molecules. Suitably substituted 3-vinylcyclopropenes (e.g., 14) should make a general route accessible due to the inherent reactivity of the strained cyclopropene to undergo ring cleavage or ring expansion. Depending upon the substitution pattern on the cyclopropene and the organometallic reagent used, it should be possible to isolate the corresponding metallabenzene valence isomers 15 and/or 16.

Using Vaska complexes and a 1,2-diphenyl derivative of 14, we have recently prepared several new "iridabenzenes" as well as the first examples of "iridabenzvalenes" (Figure 1). Like a normal benzene valence isomer, iridabenzvalene 15 cleanly rearranges to an iridabenzene upon heating. Investigations into the syntheses and interconversions of these molecules should provide a wealth of new information on the mechanisms by which transition-metal centers effect the formation and cleavage of carbon-carbon bonds.

Figure 1. Molecular structures of iridabenzene 13 and iridabenzvalene 15, respectively; ellipsoids drawn at the 30% level.

We have recently extended this new methodology for metallabenzenes to utilize other metals. The formation of a platinabenzene and a rhodabenzvalene, which are shown in Figure 2, illustrate the diversity of our route. Current work is focused on additional metal complexes (Ru, Os), as well as reactions involving new cyclopropene ligands where one or both of the phenyl substituents have been replaced by alkyl groups.

Figure 2. Molecular structures of a platinabenzene (left) and a rhodabenzvalene (right).

The work described on this web page has been generously supported by The National Science Foundation with additional contributions from The Petroleum Research Fund, The Camille and Henry Dreyfus Foundation, and The Alexander von Humboldt Foundation.

Selected Publications:

“The Renaissance of Annulene Chemistry.” E. L. Spitler, C. A. Johnson II, and M. M. Haley, Chem. Rev. 2006, 106, 5344-5386.

“Carbon Networks Based on Benzocyclynes. 6. Synthesis of Graphyne Substructures via Directed Alkyne Metathesis.” C. A. Johnson II, Y. Lu, and M. M. Haley, Org. Lett. 2007, 9, 3725-3728.

“Structure-Property Relationships of Fluorinated Donor/Acceptor Tetrakis(phenylethynyl)benzenes and Bis(dehydrobenzoannuleno)benzenes.” E. L. Spitler, J. M. Monson, and M. M. Haley, J. Org. Chem. 2008, 73, 2211-2223.

"Biscyclization Reactions in Butadiyne- and Ethyne-linked Triazenes and Diazenes: Concerted vs. Stepwise Coarctate Cyclizations." L. D. Shirtcliff, A. G. Hayes, M. M. Haley, F. Köhler, K. Hess, and R. Herges, J. Am. Chem. Soc. 2006, 128, 9711-9721.

“Reactions in the Conjugated ‘Ene-Ene-Yne’ Manifold: Five-Membered Ring Fragmentation and Ring Formation via Coarctate/Pseudocoarctate Mechanisms.” L. D. Shirtcliff, S. P. McClintock, and M. M. Haley, Chem. Soc. Rev. 2008, 37, 343-364.

"Recent Advances in Metallabenzene Chemistry." C. W. Landorf and M. M. Haley, Angew. Chem. Int. Ed. 2006, 45, 3914-3936.

“Metallabenzenes and Valence Isomers. 9. Rearrangement of Iridabenzvalenes to Iridabenzenes and/or h5-Cyclopentadienyliridium(I) Complexes: Experimental and Computational Analysis of the Influence of Silyl Ring Substituents and Phosphine Ligands.” H.-P. Wu, D. H. Ess, S. Lanza, T. J. R. Weakley, K. N. Houk, K. K. Baldridge, and M. M. Haley, Organometallics 2007, 26, 3957-3968.

Additional Publications

To Contact Dr. Haley:
Phone: 541-346-0456
haley@uoregon.edu

WEBMASTER
chem@uoregon.edu