Honors Projects

Investigation of a Heterobimetallic Effect in Reactions of Organometallics with Organic Radicals

Michelle C. Neary — Tue, 14 Dec 2010 08:28:26 PST

Allylpalladium and allylnickel compounds containing group VI-group X metal-metal bonds were synthesized using the (2-(diphenylphosphino)ethyl)cyclopentadienyl (CpPPh) bridging ligand to kinetically stabilize these bonds. As with Pd(η3-allyl)Cl(PPh3), reaction of M’{M(η3-allyl)}(CO)3(μ-η5:η1-CpPPh) (M’ = Cr, Mo, or W; M = Ni or Pd) with phenyl and trityl radicals produced only 4,4,4-triphenyl-1-butene (trityl allyl), the trityl radical-allyl coupling product. However, the reaction appears to occur through a different mechanism. A possible heterobimetallic effect renders the conversions to trityl allyl different for each group VI metal.

Synthesis of Novel Bidentate Ligands for Chelation of Metals and/or Metalloids Derived From 1,2,3 Triazoles

Sylvia Kunakom — Tue, 08 Dec 2009 12:12:46 PST

Bidentate ligands are important components of coordination complexes used for catalysis, self-assembly, and in light-emitting materials. Acetylacentonate derivatives and nitrogen atom-containing heterocycles serve as the most widely used ligand scaffolds. I report the synthesis of N,O bidentate ligands via the Cu(I)-catalyzed alkyne-azide cycoaddition (CuAAC), reported by Sharpless et al, and an oxidative functionalization of a C-H arene bond, reported by Sanford et al. I subsequently attempted to complex metals or metalloids, and the complexation of Zn(II) resulted in spectroscopically active complexes that provided promising insight in the synthesis of metal complexes used in catalysis and as fluorescent markers.

Towards a Total Synthesis of Azaspirene

Jamal Malik — Tue, 08 Dec 2009 11:00:22 PST

(chemical drawing unable to be uploaded) Azaspirene is a natural product isolated from the fungus Neosartorya sp. in 2002, wherein it was reported to be an angiogenesis inhibitor. Of particular importance in its biological activity is the fused bicyclic core, which is also the enigma that piques the interest of synthetic chemists. As chemical synthesis is as much the process of discovery along the road as it is forming the final product, the aim of this synthesis is to hopefully demonstrate a novel way of creating the fused bicycle as well as create azaspirene so that it can be used for biological testing.

Electronic Spectroscopy of AuF: Analysis of the Rotational and Hyperfine Structure

Benjamin J. Knurr — Tue, 08 Dec 2009 10:47:42 PST

High-resolution electronic spectroscopy was performed on AuF. The rotational, vibrational, electronic and hyperfine structure was resolved. Through detailed analysis, several vibrational bands of the [17.7]1-X¹Σ⁺and [17.8]0 - X¹Σ⁺transitions were assigned. At least squares fit of the data collected by laser excitation spectroscopy from the transitions has provided the most accurate determination of the rotational, vibrational and electronic constants of the [17.7]1 and [17.8]0 states for AuF to date. Subsequent efforts in hyperfine analysis showed a discrepancy in the original assignment of the [17.7]1 state. Through application of quantum mechanics, the correct assignment of ³Δ₁ state mixed with a lower-lying ¹Π₁ state was realized.

Quantification of Methyl Mercury and Selenium in Preserved Common Loon Feathers by Cold Vapor and Hydride Generation Flame Atomic Absorption Spectrometry

Amanda K. Hulke — Mon, 04 May 2009 08:21:34 PDT

Common Loon (Gavia immer) feathers serve as excellent environmental indicators of anthropogenic mercury infiltration into aquatic ecosystems. Sequestration into feathers, a defense mechanism possibly facilitated by selenium, has not been extensively studied in historical specimens. We sought to determine concentrations of methyl mercury and selenium within feathers obtained from museum specimens. Extraction methods were standardized using DORM-3 and DOLT-3, certified biological samples. Analysis was performed using a Buck Scientific 410 Cold Vapor Mercury Analyzer and a 420 Continuous Flow Hydride Generator coupled to a Buck 210 Atomic Absorption Spectrometer. A method for methyl mercury was validated and initial concentrations determined.

Computational Comparison of Tropospheric Criegee Intermediate Unimolecular and Bimolecular Reaction Kinetics

Matthew R. Hermes — Mon, 04 May 2009 08:16:49 PDT

Carbonyl oxides, or Criegee intermediates, formed in ozonolysis, are very difficult to isolate and study experimentally. Computation has been used to clarify how Criegee intermediates in the troposphere contribute to hydroxyl radical levels and to acid rain. Quantum chemistry, transition state theory, and RRKM theory were used to predict rate constants and branching ratios for the unimolecular and bimolecular reaction of simple Criegee intermediates with water, sulfur dioxide, and nitrogen dioxide. Analysis finds that tunneling accelerates hydrogen shift rates into competition with water addition rates at equilibrium vapor pressure, sulfur dioxide and water both react faster with carbonyl oxides than does nitrogen dioxide, and that sulfur dioxide adducts decompose promptly while some fraction of nitrogen dioxide adducts are collisionally stabilized at atmospheric pressure.

An Investigation of the Zipper Reaction in Aromatic Substrates

Erica Schultz — Fri, 26 Sep 2008 13:13:34 PDT

The alkynol zipper reaction efficiently isomerizes an internal triple bond to a terminal triple bond over a straight carbon chain. However, this same reaction is inefficient for isomerizing triple bonds that are attached to aromatic substrates (1). This project attempts to optimize the zipper reaction on both alkynol and alkynyl-aromatic substrates by investigating the use of various amines reagents and reaction conditions. Upon discovery of pseudo-optimal conditions for the aromatic zipper (pictured in hard copy in library), we investigated the mechanism and formation of various alkene,and allene intermediates via No-D 'H NMR spectroscopy.

A Computational Analysis of Bimolecular Processes Involving Carbonyl Oxides in the Atmosphere

Emily J. Guinn — Mon, 05 May 2008 07:37:54 PDT

Carbonyl oxides, which are formed from alkenes through ozonolysis, play an important role in atmospheric chemistry. This study examined their rearrangement into carboxylic acids with the aid of another molecule that acts as a catalyst. Because carbonyl oxides are very unstable, computation is useful in studying this reaction. The bimolecular pathways for the reaction of formaldehyde oxide with CO2, SO2, NO2 and NO were studied. The geometries of all structures involved and their energies were calculated using several computational methods: BB1K/6-31+G(d,p), B3LYP/6-31+G(d,p), CBS-QB3, G3 and CBS-APNO. In each pathway, the carbonyl oxide and catalyst molecule formed a cyclic adduct, which then broke apart into a carboxylic acid and the catalyst. Depending on the catalyst used, the adduct could form and break apart in one or more steps or other pathways forming different products were possible. These reactions were also studied with a methyl group on the carbonyl oxide. The relative energies for the reaction were similar to the non-methylated pathways, although the placement of the methyl group on either the syn or anti position affected the reaction mechanism and energy. Transition state theory was used to determine the rate of the first step in each reaction and indicated that the SO2 reaction should occur at the highest relative rate. RRKM theory was used to determine branching ratios for the reactions.

Rotational and Hyperfine Structure in the Spectra of TaO and ReO

Kara J. Manke — Wed, 16 May 2007 13:17:11 PDT

We have recorded hyperfine resolved spectra of the B–X and C–X electronic transitions of TaO and the 712-nm band of ReO. A Ti:sapphire ring laser was used to analyze TaO and ReO molecules produced in a hollow cathode discharge. We achieved hyperfine resolution using the sub-Doppler technique of inter-modulated florescence. A least-squares fit of the transition frequencies was used to determine improved values for the rotational parameters and values for the magnetic dipole and electric quadrupole parameters of these states. These have allowed for an elucidation of the ground state electronic configurations in TaO and ReO.

Towards the Total Synthesis of Clathculin B

Susan G. Brown — Wed, 02 May 2007 08:19:16 PDT

The two novel acyclic diaza alkenynes, clathculins A and B, were isolated from the Indo-Pacific sponge Clathrina aff. reticulum, collected in Sodwana Bay, South Africa, by the Rudi research group at the Tel-Aviv University. They were isolated as an unstable mixture and their structures were reported via hydrogenation of the compounds to the saturated analogs. Our work surrounding these compounds has been toward their synthesis and characterization.