Organometallic transition metal complexes and their reactions; Mechanism of alkene-alkyne metathesis, catalyzed by ruthenium carbene complexes; Organic and inorganic synthesis, IR, NMR, UV/Visible and EPR spectroscopies, electrochemistry, and kinetics
562 Natural Sciences Complex
Buffalo NY, 14260
Phone: (716) 645-4205
Fax: (716) 645-6963
Organometallic chemistry, metal clusters, and homogeneous catalysis.
Our research concerns various aspects of transition metal complexes and their reactions. Students have the opportunity to learn organic and inorganic synthetic methods, IR, NMR, UV/Visible and EPR spectroscopies, electrochemistry, and kinetics. This broad background is especially valuable training for multi-disciplinary industrial research and development.
One project, in collaboration with Steven Diver’s research group, concerns the mechanism of alkene-alkyne metathesis, catalyzed by ruthenium carbene complexes. Our contribution concerns kinetic studies of this reaction. The rate is monitored by using IR spectroscopy, UV/visible spectroscopy, or gas chromatography to measure reactant and product concentrations. The rate law is determined by varying the concentrations of catalyst, alkyne, alkene and other reagents. Relative rates determined for alkynes and alkenes having different functional groups allow us to define the steric and electronic properties of the activated complex. These studies, combined with Diver’s complementary synthetic studies, will paint a complete picture of the reaction, which will allow synthetic chemists better control over this important methodology.
A second area of research concerns low-dimensional materials based upon metal coordination polymers. Recent attention has been drawn to the design of redox-active ligands for electrochemically controlling reactivity of transition metals, with applications in catalysis, sensors, and “molecular switches.” By electrochemically changing the oxidation state of the ligand a metal complex can be interconverted between two (or more) states of reactivity. Our research concerns monometallic and polymetallic complexes with electroactive polyoxolene ligands, for which one can expect redox processes associated with the metal framework and with the ligands. The term “polyoxolene” to refer to polycyclic aromatics which contain two or more oxygen substituents. These complexes usually show rich electrochemistry with ligand-localized redox processes, in addition to metal-localized redox processes.
Reactions of polyoxolenes such as alizarin, anthragallol, purpurin, or rufigallol provide a variety of new complexes, one of which is shown below. We have fully characterized these products by IR, NMR, UV/visible, and electrochemistry. The 1-e oxidation products have been characterized by EPR spectroscopy. The goal of this research is to synthesize mono- and bimetallic complexes containing polyoxolene ligands in a variety of coordination modes, and to examine changes in electrochemistry due to changes in coordination mode, pH, and reactions with donor ligands. Redox induced changes in coordination of the polyoxolene may be used to induce chemical processes (such as catalysis) or to act as energy or signal storage systems. Polymers based upon these complexes should serve as 1-dimensional conductors.