John L. Bear
Professor and Dean, College of Natural Sciences and Mathematics
	Office: 214 SR-1 Phone: (713) 743-2620 Email: jbear@uh.edu Education B.S. Southwest Texas State University, 1955 M.A. Southwest Texas State University, 1956 Ph.D., Texas Tech, 1960 Honors, Fellowships, etc. Research Associate, Florida State Univ., 1960 Assistant Professor, Florida State Univ., 1962 Chair, Dept. of Chemistry, UH, 1975 - 1992 Dean, College of Natural Sciences and Mathematics

Research Interests

Over the past few years our research has been aimed at understanding structure reactivity relationships of several group VIII-B dinuclear transition metal complexes and to use this information to control the chemical and electrochemical reactivity at the metal centers. Among these complexes, the dirhodium and diruthenium compounds are the most sensitive to the nature of the axial and bridging ligands with respect to variation in their chemical and electrochemical behavior. The reactivity at a metal center depends on the sigma donor-pi acceptor properties of the bridging ligand, the geometric bonding arrangement, and the steric environment about the reactive site of the metal. For example the Rh24+/Rh25+ redox couple can be controlled over the range from approximately 2.0 V for Rh2(tfac)4 to -0.63V for Rh2(ap)4(CCH)2 (tfac = trifluoroacetate ion; ap = 2-anilino-pyridinate ion). The same type of control is true for other dirhodium redox couples corresponding to the formation of (MI - MII), (MII - MII), (MII - MIII), (MIII - MIII), and (MIII - MIV) oxidation states. The objectives of our current research are: (i) to investigate the mechanism of bridging ligand exchange reactions and determine the factors that control the different geometric isomers formed; (ii) to investigate structure-reactivity relationships of dirhodium and dirhuthenium transition metal complexes with a variety of homo- and hetero-do nor bridging ligand and use this information to understand and control metal centered reactivity; (iii) to investigate the chemistry of the three geometric isomers of the family of complexes with the formula Ru2(F(5-x)Hxap)4Cl. These complexes exhibit a very different chemistry which is related to their unique structural and electronic features. (iv) to investigate the factors that determine the electronic electronic structure of diruthenium complexes.