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Inorganic Chemistry: Syntheses and uses of transition metal and lanthanide organometallics, inorganic photochemistry.

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Our general aim is to use organometallic reagents to either model the chemistry which occurs in catalytic systems or to develop new metal-mediated ways of effecting conversions of organic species. This has led to efforts in the area of organolanthanide chemistry and in the chemistry of transition metal ketene complexes.

Ketenes are of interest because: a) they have been postulated as intermediates in the conversion of synthesis gas (CO/H₂) to oxygen-containing products; and b) they are highly unsaturated and potentially able to undergo several sequential bond-forming transformations. Ketenes are able to bind transition metals via at least two modes, involving either C=C or C=O p complexation. We have focused on the latter, and are interested in understanding the mechanism by which such bound ketenes undergo C=C cleavage to CO and carbene (R₂C:). Also, we not that C=O complexation of unsymmetrical ketenes is highly selective, and that nucleophilic attack can be used in the formation of E enolate isomers.

Other research has centered on the syntheses and luminescence spectroscopy of organocerium (III) compounds. We have prepared strerically accessible compounds of this large lanthanide ion (which has a ground electronic state of 4f1), and found that they all luminesce from a 4f-5d excited state. Since cerium 5d orbitals figure prominently in metal-ligand bonding, the wave-lengths of the luminescent emissions vary significantly (over a range of 300nm) with the nature of the ligand sphere. This will allow the use of cerium (III) as a sensitive luminescent probe of metal binding sites in complex media, and as an indicator of the nature of the metal ligand bonding.

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Selected Publications

• “Facile Synthesis of a,b-Unsaturated Niobium Acyls via g-Hydride Abstraction” Hneihen, A. S.; Fermin, M. C; Maas, J. J.; Bruno, J. W. J. Organomet. Chem. 429, C33-C37 (1992).
• “FT-IR Analysis of Toluene Hydrogenation Reactions on Reduced Alumina-Supported Catalysts” DeCanio, E. C.; Storm, D. A.; Bruno, J. W. Progress in Catalysis, 231 (1992).
• “Equilibrium Acidities of Some Transition Metal Acyl Compounds” Fermin, M. C.; Thiyagarajan, B.; Bruno, J. W. J. Am. Chem. Soc.115, 974 (1993).
• “Activation of Niobocene-Ketene Complexes: Ligand-Centered Syntheses of Hydrides and Acyls” Fermin, M. C.; Hneihen, A. .; Maas, J. J; Bruno, J. W. Organometallics 12, 1845 (1993).
• “MAS ¹H NMR Characterization of g-Alumina and Modified g-Aluminas” DeCanio, E. C.; Edwards, J. C.; Bruno, J. W. J. Catal. 148, 76 (1994).
• “Luminescence Studies of Cerium(III) Incorporated in Silica Gels Prepared Using Sol-Gel Methods” Rand, E. R.; Smuckler, M. B.; Go, E.; Bradley, M. S.; Bruno, J. W. Inorg. Chim. Acta 233, 71 (1995).
• “Synthesis, Structure, and Redox Reactivity of a Substituted Niobocene Formaldehyde Complex. The Importance of Hydrogen-Bonding in the Redox Chemistry” Thiyagarajan, B.; Michalczyk, L.; Bollinger, J. C.; Huffman, J. C.; Bruno, J. W. Organometallics 15, 1989 (1996).
• “Generation of Organoniobium(II) Radicals and Synthesis of Heterometallic Niobium-Mercury Compounds” Thiyagarajan, B.; Michalczyk, L.; Bollinger, J. C.; Bruno, J. W. Organometallics 15, 2588 (1996).
• “Electrophilic Attack on the Carbon Terminus of a Niobium-Bound Formaldehyde Ligand” Thiyagarajan, B.; Kerr, M. E.; Bollinger, J. C.; Young, V. G., Jr.; Bruno, J. W. Organometallics 16, 1331 (1997).
• “Synthesis and Reactivity of Niobium-Vinylketene Complexes Exhibiting Ketene C,O Complexation” Kerr, M. E.; Bruno, J. W. J. Am. Chem. Soc. 119, 3183 (1997).
• “Effects of the Niobium(V) Center on the Energetics of Ligand-Centered Proton and Hydrogen Atom Transfer Reactions in Acyl and Alkoxide Complexes” Kerr, M. E.; Zhang, X.-M.; Bruno, J. W. Organometallics 16, 3249 (1997).
• “Niobium-Mercury Hetermetallic Compounds as Sources of Niobium(II): Radical Paths to Organoniobium Species,” Thiyagarajan, B.; Michalczyk, L.: Young, V.G., Jr.; Bruno, J.W. Organometallics 16, 5884 (1997).
• “Hydride Affinities of Arylcarbenium Ions and Iminium Ions in Dimethyl Sulfoxide and Acetonitrile,” Zhang, X.-M.; Bruno, J.W.; Enyinnaya, E. J. Org. Chem. 63, 4671 (1998).
• “Thermodynamic and Kinetic Studies of Hydride Transfer for a Series of Molybdenum and Tungsten Hydrides,” Sarker, N.; Bruno, J.W.; J. Am. Chem. Soc. 121, 2174 (1999).
• “Hydride and Proton Transfer Reactions of Niobium-Bound Ligands. Synthetic and Thermodynamic Studies of Ketene, Enacyl and Vinylketene Complexes,” Kerr, M.E.; Sarker, N.; Hneihen, A.S.; Schulte, G.S.; Bruno, J.W. Organometallics 2000, 19, 901-912.
• “Process for High Temperature Production of Organic Aerogels,” Mendenhall, R.; Andrews, G.; Bruno, J.W.; Albert, D.F., U.S. Patents 6,077,876 and 6,090,861, 2000.
• “Use of Niobium(III) and Niobium(V) Compounds in Catalytic Imine Metathesis under Mild Conditions,” Bruno, J.W.; Li, X.J. Organometallics 2000, 19, 4672-4674.
• “Thermodynamic Studies of Hydride Transfer for a Series of Niobium and Tantalum Compounds,” Sarker, N.; Bruno, J.W. Organometallics 2001, 20, 55-61.
• “Supercritical Methanol Drying as a Convenient Route to Phenolic-Furfural Aerogels,” Albert, D.F.; Andrews, G.R.; Mendenhall, R.S; Bruno, J.W. J. Non-Cryst. Solids 2001, 296, 1-9.
• “Chelating Aryloxide Ligands in the Synthesis of Niobium, Tantalum, and Titanium Compounds,” Michalczyk, L.; de Gala, S.; Bruno, J.W. Organometallics 2001, 20, 5547-5556.
• “Sterically-Congested Bisphosphite Ligands for the Catalytic Hydrosilation of Ketones,” Smith, A.R.; Bruno, J.W.; Pastor, S.D. Phosphorus, Sulfur, Silicon 2002, 177, 479-485.
• “Hydricities of BzNADH, C₅H₅Mo(PMe₃)(CO)₂H, and C₅Me₅Mo(PMe₃)(CO)₂H in Acetonitrile,” Ellis, W. W.; Raebiger, J. W.; Curtis, C. J.; Bruno, J. W.; DuBois, D. L. J. Amer. Chem. Soc. 2004,  126,  2738-2743.

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Education

B.A. 1978 Augustana College

M.S. 1979 Northwestern University

Ph.D. 1983 Northwestern University