A5081221319- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Organometallic Complex Synthesis and Catalysis
- Crystallography and molecular interactions
- Carbon dioxide utilization in catalysis
- biodegradable polymer synthesis and properties
- Coordination Chemistry and Organometallics
- Synthesis and characterization of novel inorganic/organometallic compounds
- Lanthanide and Transition Metal Complexes
- Radioactive element chemistry and processing
- Environmental remediation with nanomaterials
- Polymer Science and PVC
- Inorganic Chemistry and Materials
- Magnetism in coordination complexes
- Synthetic Organic Chemistry Methods
- Ionic liquids properties and applications
- Organoboron and organosilicon chemistry
- Advanced Polymer Synthesis and Characterization
- Microplastics and Plastic Pollution
- Recycling and Waste Management Techniques
- Chemical Synthesis and Reactions
- Radiopharmaceutical Chemistry and Applications
- History and advancements in chemistry
- Silicone and Siloxane Chemistry
- Analytical chemistry methods development
University of Southern California
2020-2025
Southern California University for Professional Studies
2020
Los Angeles City College
2020
University of California, Irvine
2011-2018
University of Minnesota
2017-2018
University of Minnesota System
2018
Minneapolis Institute of Arts
2018
University of California System
2014-2017
Irvine Valley College
2014-2017
Flash reduction of Cp'3U (Cp' = C5H4SiMe3) in a column potassium graphite the presence 2.2.2-cryptand generates crystalline [K(2.2.2-cryptand)][Cp'3U], first isolable molecular U(2+) complex. To ensure that this was not U(3+) hydride, [K(2.2.2-cryptand)][Cp'3UH], which could be crystallographically similar, hydride complex synthesized by addition KH to and H2 confirmed different compound. Density functional theory calculations indicate 5f(3)6d(1) quintet ground state for [Cp'3U](-) anion...
The Ln3+ and Ln2+ complexes, Cp′3Ln, 1, (Cp′ = C5H4SiMe3) [K(2.2.2-cryptand)][Cp′3Ln], 2, respectively, have been synthesized for the six lanthanides traditionally known in +2 oxidation states, i.e., Ln Eu, Yb, Sm, Tm, Dy, Nd, to allow direct structural spectroscopic comparison with recently discovered ions of Pr, Gd, Tb, Ho, Y, Er, Lu 2. 2-La 2-Ce were also prepared first all same coordination environment both +3 states. show unusual feature that Ln–(Cp′ ring centroid) distances are only...
The first molecular complexes of holmium and erbium in the +2 oxidation state have been generated by reducing Cp′3Ln [Cp′ = C5H4SiMe3; Ln Ho (1), Er (2)] with KC8 presence 18-crown-6 Et2O at −35 °C under argon. Purification crystallization below gave isomorphous [(18-crown-6)K][Cp′3Ln] [Ln (3), (4)]. three Cp′ ring centroids define a trigonal-planar geometry around each metal ion that is not perturbed location potassium crown cation near one K–C(Cp′) distances 3.053(8)–3.078(2) Å. metrical...
Mechanistic studies involving synergistic experiment and theory were performed on the perfectly alternating copolymerization of 1-butene oxide carbic anhydride using a (salph)AlCl/[PPN]Cl catalytic pair. These showed first-order dependence polymerization rate epoxide, zero-order cyclic anhydride, catalyst only if two members pair are treated as single unit. Studies model complexes that mixed alkoxide/carboxylate aluminum intermediate preferentially opens over epoxide. In addition,...
Structural, spectroscopic, and DFT analysis of the first molecular complexes Th<sup>2+</sup> indicate they have a 6d<sup>2</sup> electron configuration type expected for transactinide ions Rf<sup>2+</sup> Db<sup>3+</sup>.
The recently reported series of divalent lanthanide complex salts, namely [K(2.2.2-cryptand)][Cp'3Ln] (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm; Cp' C5H4SiMe3) and the analogous trivalent complexes, Cp'3Ln, have been characterized via dc ac magnetic susceptibility measurements. salts complexes [Cp'3Dy](-) [Cp'3Ho](-) exhibit moments 11.3 11.4 μB, respectively, which are highest to date for any monometallic molecular species. measured at room temperature support assignments a...
A new series of Ln3+ and Ln2+ complexes has been synthesized using the tris(aryloxide)arene ligand system, ((Ad,MeArO)3mes)3-, recently used to isolate a complex U2+. The triphenol precursor, (Ad,MeArOH)3mes, reacts with amides, Ln(NR2)3 (R = SiMe3), form [((Ad,MeArO)3mes)Ln] complexes, 1-Ln. Crystallographic characterization was achieved for Ln Nd, Gd, Dy, Er. 1-Ln can be reduced potassium graphite in presence 2.2.2-cryptand (crypt) highly absorbing solutions properties consistent...
The reactivity of the recently discovered Th2+ complex [K(18-crown-6)(THF)2][Cp″3Th], 1 [Cp′′ = C5H3(SiMe3)2-1,3], with hydrogen reagents has been investigated and found to provide syntheses new classes thorium hydride compounds. Complex reacts [Et3NH][BPh4] form terminal Th4+ Cp″3ThH, 2, a reaction that formally involves net two-electron reduction. also in solid state solution H2 mixed-valent bimetallic product, [K(18-crown-6)(Et2O)][Cp″2ThH2]2, 3, which was analyzed by X-ray...
Tandem hydrodechlorination/Friedel–Crafts alkylation of poly(vinyl chloride) (PVC) is achieved using silylium ion catalysts to prepare new styrenic copolymers polyethylene.
Ln<sup>II</sup>(C<sub>5</sub>H<sub>4</sub>SiMe<sub>3</sub>)<sup>1−</sup>have been characterized by XANES and DFT.
A new option for stabilizing unusual Ln<sup>2+</sup> ions has been identified in the reaction of (C<sub>5</sub>H<sub>4</sub>SiMe<sub>3</sub>)<sub>3</sub>Ln (Ln = La, Ce) with potassium graphite and 2.2.2-cryptand benzene.
The synthesis of 4fn Ln3+ complexes the tris(aryloxide) mesitylene ligand, ((Ad,MeArO)3mes)3–, with Ln = La, Ce, Pr, Sm, and Yb, their reduction potassium have revealed that this ligand system can be redox active some metals. Protonolysis [Ln(N(SiMe3)2)3] (Ln Yb) tris(phenol) (Ad,MeArOH)3mes yielded [((Ad,MeArO)3mes)Ln] Yb), 1-Ln. Single electron each complex, 1-Ln, using reduced products, [K(2.2.2-cryptand)][((Ad,MeArO)3mes)Ln] 2-Ln. Sm Yb properties consistent presence Ln2+ ions...
Reaction of poly(vinyl chloride) (PVC) with 5 equiv. triethyl silane in THF, the presence situ generated (xantphos)RhCl catalyst, results partial reduction PVC via hydrodechlorination to yield chloride-co-ethylene). Increasing catalyst loading or using N,N-dimethylacetamide (DMA) as a solvent both diminished selectivity for hydrodechlorination, promoting competitive dehydrochlorination reactions. 2 sodium formate THF affords excellent along complete dechlorination, yielding polyethylene-like...
The reactivity of the unusual oxyaryl dianionic ligand, (C6H2(t)Bu2-3,5-O-4)(2-), in Bi(3+) NCN pincer complex Ar'Bi(C6H2(t)Bu2-3,5-O-4), 1, [Ar' = 2,6-(Me2NCH2)2C6H3] has been explored with small molecule substrates and electrophiles. first insertion reactions CO2 COS into Bi-C bonds are observed this ligand complex. These generate new dianions that have quinoidal character similar to 1. oxyarylcarboxy oxyarylthiocarboxy ligands were identified by X-ray crystallography...
The tris(cyclopentadienyl) yttrium complexes Cp3Y(THF), CpMe3Y(THF), Cp″3Y, Cp″2YCp, and Cp″2YCpMe [Cp = C5H5, CpMe C5H4Me, Cp″ C5H3(SiMe3)2] have been treated with potassium graphite in the presence of 2.2.2-cryptand to search for more stable examples featuring recently discovered Y2+ ion first isolated [K(18-crown-6)][Cp′3Y] [K(2.2.2-cryptand)][Cp′3Y], 1-Y (Cp′ C5H4SiMe3). Reduction generates dark solutions like that 1-Y, EPR spectra contain doublets g values between 1.990 1.991 hyperfine...
Aliphatic polyesters have received considerable attention in recent years due to their biodegradability and biocompatible, mechanical, thermal properties that can make them a suitable alternative today's commercialized polymers. The ring-opening copolymerization (ROCOP) of epoxides cyclic anhydrides is route synthesize diverse array could be useful many applications. However, the catalysts used rarely consider biocompatible case any are left polymer. To best our knowledge, we report first...
Lewis acidic silylium ions are used to completely remove Cl from poly(vinyl chloride) (PVC) in clean and commercial products through hydrodechlorination. Reaction conditions were found impact the branching resulting polyethylene (PE).
Hydrodechlorination of poly(vinyl chloride) (PVC) directly to polyethylene (PE) represents a way repurpose PVC waste, while avoiding toxic and/or corrosive byproducts that are produced at the end life. Prior studies identified rhodium‐catalyzed route hydrodechlorinate form PE products with sodium formate as hydrogen source. While all chlorine could be removed PE‐like polymers, reaction was slow and side reactions introduced undesirable cross‐links in polymer product. In this work,...
Lanthanide chloride salts, with a cocatalyst, are used as near “one-size-fits-all” catalyst system to perform the ring-opening copolymerization of diverse epoxides and cyclic anhydrides.
Dinitrogen can be reduced by photochemical activation of the trivalent rare-earth-metal bis(pentamethylcyclopentadienyl) allyl complexes (C5Me5)2Ln(η3-C3H4R) (Ln = Y, Lu; R H, Me) to form (N═N)2– [(C5Me5)2Ln]2(μ-η2:η2-N2). This demonstrates that productive organolanthanide photochemistry is not limited unusual (η3-C5Me4H)− ligand in heteroleptic (C5Me5)2(C5Me4H)Ln and (C5Me5)(C5Me4H)2Ln. Photolytic (C5Me5)2Ln(η3-C3H5) Lu) presence isoprene provides a rare photopolymerization route...
Dinitrogen can be reduced by photochemical activation of the Ln(3+) mixed-ligand tris(cyclopentadienyl) rare-earth complexes (η(5)-C5Me5)(3-x)(C5Me4H)(x)Ln (Ln = Y, Lu, Dy; x 1, 2). [(C5Me4R)2Ln]2(μ-η(2):η(2)-N2) products (R H, Me) are formed in reactions which N2 is to (N═N)(2-) and (C5Me4H)(-) oxidized (C5Me4H)2. Density functional theory indicates that this unusual example photochemistry rationalized absorptions involving (η(3)-C5Me4H)(-) ligands.
Raman spectra have been collected on single crystals of over 20 different rare earth complexes containing reduced dinitrogen ligands to determine if these data will correlate with periodic properties or relative stability. Four types were examined: [(C5Me5)2Ln]2(μ-η(2):η(2)-N2), 1-Ln, [(C5Me4H)2(THF)Ln]2(μ-η(2):η(2)-N2), 2-Ln, [(C5H4Me)2Ln]2(μ-η(2):η(2)-N2), 3-Ln, and {[(Me3Si)2N]2(THF)Ln}2(μ-η(2):η(2)-N2), 4-Ln. Although each the contains a side-on bound ligand that is formally (N2)(2-),...
Catalytic methods for the cyclodepolymerization and solvolysis of polyesters polycarbonates have been realized with a molecular cobalt catalyst. Nascent strategies to modify these use in mixed plastic waste streams are identified.
Monometallic yttrium β-diketiminate complexes are active and controlled catalysts for perfectly alternating ring-opening copolymerization of 1-butene oxide phthalic anhydride under mild conditions. β-Diketiminate ligands with pendant neutral donors were targeted to identify both the impact donor strength number on rates polymerization presence undesirable side reactions. Initiating groups also varied between alkyls, chlorides, alkoxides. In a cocatalyst, studied minimal reactions, whereas...