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Timothy P. Hanusa

Title and Contact Information

Professor of Chemistry
Office: 7864 SC
Phone: (615) 322-4667
Email   Website


Ph.D., Indiana University, 1983


Organometallic Chemistry
Inorganic Chemistry

Research Interests

Synthetic inorganic and organometallic chemistry of the main group, transition metal, and rare earth elements. Particular emphasis on mechanochemical synthesis by grinding or milling

Ligand design, including the use of steric effects and cation-π interactions, to control the structure and reactivity of organometallic and coordination complexes

Computational investigations of bonding, structure, and dispersion effects

In the News

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Mechanochemical synthesis
Solvent-free reactions are a characteristic feature of mechanochemistry, which uses mechanical action (e.g., impact and friction) to generate the energy needed for chemical reactions. The cracking of crystals by grinding can fracture bonds and create radicals in ways that do not occur in a solvent, and the outcome of mechanochemical reactions need not be (are often are not!) the same as in solution. Solid-state syntheses provide the opportunity to investigate new compounds not otherwise obtainable. This might be because available solvents interfere with the interaction of the reagents, or because solvent molecules may bind irreversibly to the product, and change its structure and reactivity.

We are particularly interested in low-coordinate metal complexes, as they can display higher reactivity than solvated species. The tris(allyl)aluminum species Al[A´3] (A´= 1,3-(SiMe3)2C3H3)), for example, can be made mechanochemically in a few minutes of grinding, and reacts immediately with oxygen-containing organics, unlike the much slower reactions of solvated species.

Control of stereochemistry in solid-state organometallic synthesis is also under investigation. For example, the group 15 compounds M[A´]3 (M = As, Sb) exist as both symmetric (C3) and asymmetric (C1) diastereomers, but mechanochemical synthesis increases the amount of the C1 diastereomer. This appears to be related to the particular lattice structures of the solid state starting materials, and provides a unique handle for designing stereocontrolled reactions specifically for mechanochemical initiation.

New Ligand Design. Main-group metals (groups 1, 2, 12, 13) and the lanthanides usually have only one or at most two readily available oxidation states, which limits the range of chemistry possible from their metal complexes. We are developing ligands that put metals into unusual coordination environments, potentially overcoming this restriction. For instance, a set of two cyclopentadienyl (Cp) ligands, when bridged with a silyl group [R2SiCp2]2-, necessarily carries a dinegative charge. If a phosphonium bridge is used instead (i.e., [R2P+Cp2]-), the ligand is uninegative, and when bound to a group 2 metal, the metal coordination environment is similar to that of a trivalent lanthanide. Using this approach, we have made a calcium amido complex that is structurally similar to a samarium analogue.

We are investigating other ligand types besides cyclopentadienyl (indenyls, allyls) so as to extend the concept to a wider range of applications, including catalysis with earth-abundant main-group elements (alkali/alkaline-earth metals).

Computational investigations of bonding, structure, and dispersion effects in inorganic/organometallic systems. Unusual structural arrangements often require computational analysis in order to generate a complete picture of their origins and consequences for structure and reactivity. Computational modeling of cation-pi bonding, such as between K+ and the double bonds in the allyl ligands in the complex K[ZnA´3], has demonstrated that the interaction can be ≥ 100 kJ mol-1 in strength, and that it also contributes to the templating of the ligands, resulting in the highly symmetric (C3 axis) complex. Studies of the effect of cation-pi interactions on reactivity are ongoing.


Selected Publications

Boyde NC, Chmely SC, Hanusa TP, Rheingold AL, Brennessel WW. Structural Distortions in M[E(SiMe3)(2)](3) Complexes (M = Group 15, f-Element; E = N, CH): Is Three a Crowd? Inorganic Chemistry. 2014, 18 (53): 9703-9714.

Lichtenberg C, Spaniol TP, Peckermann I, Hanusa TP, Okuda J. Cationic, Neutral, and Anionic Allyl Magnesium Compounds: Unprecedented Ligand Conformations and Reactivity Toward Unsaturated Hydrocarbons. Journal of the American Chemical Society. 2013, 135 (2): 811-821.

Engerer LK, Carlson CN, Hanusa TP, Brennessel WW, Young VG. Sigma- vs pi-Bonding in Manganese(II) Allyl Complexes. Organomettallics. 2012, 31 (17): 6131-6138.

Jochmann P, Spaniol TP, Chmely SC, Hanusa TP, Okuda J. Preparation, Structure, and Ether Cleavage of a Mixed Hapticity Allyl Compound of Calcium. Organomettallics. 2011, 30 (19): 5291-5296.

Bierschenk EJ, Wilk NR, Hanusa TP. 2,4-Pentanediolate as an Alkoxide/Diketonate "Hybrid" Ligand and the Formation of Aluminum and Zirconium Derivatives. InOrganic Chemistry. 2011, 50 (23): 12126-12132.

Engerer LK, Hanusa TP. Geometric Effects in Olefinic Cation-pi Interactions with Alkali Metals: A Computational Study. Journal of Organic Chemistry. 2011, 76 (1): 42-49.

ChmelySC, Hanusa TP, Brennessel WW. Bis(1,3-trimethylsilylallyl)beryllium. Angewandte Chemie-International Edition. 2010, 49 (34): 5870-5874.

Quisenberry KT, White RE, Hanusa TP, Brennessel WW. Allyl complexes of the heavy alkaline-earth metals: molecular structure and catalytic behavior. New Journal of Chemistry. 2010, 34 (8): 1579-1584.

Schmidt BW, Rogers BR, Gren CK, Hanusa TP. Carbon incorporation in chemical vapor deposited aluminum oxide films. Thin Solid Films. 2010, 518 (14): 3658-3663.

Crisp JA, Meier RM, Overby JS, Hanusa TP, Rheingold AL, Brennessel WW. Indenyl Complexes of Manganese(II). Conformational Flexibility of the Manganese(II) (RnC9H7-n) Bond. Organometallics. 2010, 29 (10): 2322-2331.

Chmely SC, Hanusa TP. Complexes with Sterically Bulky Allyl Ligands: Insights into Structure and Bonding. European Journal of Inorganic Chemistry. 2010, 9: 1321-1337.

Schmidt BW, Sweet WJ, Bierschenk EJ, Gren CK, Hanusa TP, Rogers BR. Metal-organic chemical vapor deposition of aluminum oxide thin films via pyrolysis of dimethylaluminum isopropoxide. Journal of Vacuum Science & Technology A. 2010, 28 (2): 238-243.

Meredith MB, McMillen CH, Goodman JT, Hanusa TP. Ambient temperature imidazolium-based ionic liquids with tetrachloronickelate(II) anions. Polyhedron. 2009, 28 (12): 2355-2358.

Gren CK, Hanusa TP, Rheingold AL. Solvent-resistant structures of base-free lithium and potassium allyl complexes, M[(SiMe3)(n)C3H5-n] (M = Li, n=3; M = K, n=2). Main Group Chemistry. 2009, 8 (4): 225-235.

Hanusa T. Exploring the Relationships Between Main Group and f-Element Chemistry Transfer of ownership for 2010 Preface. Main Group Chemistry. 2009, 8 (4): 223-224.

Harvey MJ, Burkey DJ, Chmely SC, Hanusa TP. Stability of cyclopentadienyl aryloxide complexes of calcium and barium. Journal of Alloys and Compounds. 2009, 488 (2): 528-532.

Johns AM, Chmely SC, Hanusa TP. Solution Interaction of Potassium and Calcium Bis(trimethylsilyl)amides; Preparation of Ca[N(SiMe3)(2)](2) from Dibenzylcalcium. Inorganic Chemistry. 2009, 48 (4): 1380-1384.

Chmely SC, Carlson CN, Hanusa TP, Rheingold AL. Classical versus Bridged Allyl Ligands in Magnesium Complexes: The Role of Solvent. Journal of the American Chemical Society. 2009, 131 (18): 6344-+.

Meredith MB, Crisp JA, Brady ED, Hanusa TP, Yee GT, Pink M, Brennessel WW, Young VG. Tunable Spin-Crossover Behavior in Polymethylated Bis(indenyl)chromium(II) Complexes: The Significance of Benzo-Ring Substitution. Organometallics. 2008, 27 (21): 5464-5473.

Brady ED, ChmelySC, JayaratneKC, HanusaTP, Young VG, Jr. s-Block Metal Complexes of the Bis(tetramethylcyclopentadienyl) Phosphonium Diylide [Me(t-Bu)P(C5Me4)2] . Organometallics. 2008, 27 (7): 1612-1616.

Quisenberry KT, Gren CK, White RE, Hanusa TP, Brennessel WW. Trimethylsilylated allyl complexes of the heavy alkali metals, M[1,3-(SiMe3)(2)C3H3](thf)(n) (M = K, Cs). Organometallics. 2007, 26 (17): 4354-4356.

White RE, Hanusa TP, Kucera BE. Compositional variations in monomeric trimethylsilylated allyl lanthanide complexes. Journal of Organometallic Chemistry. 2007, 692 (16): 3479-3485.