A5080632985- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Organometallic Complex Synthesis and Catalysis
- Crystallography and molecular interactions
- Coordination Chemistry and Organometallics
- Asymmetric Hydrogenation and Catalysis
- Synthesis and characterization of novel inorganic/organometallic compounds
- Lanthanide and Transition Metal Complexes
- Catalysis for Biomass Conversion
- Inorganic Chemistry and Materials
- Hydrogen Storage and Materials
- Biofuel production and bioconversion
- Ammonia Synthesis and Nitrogen Reduction
- Radioactive element chemistry and processing
- Magnetism in coordination complexes
- High-Energy Particle Collisions Research
- Particle physics theoretical and experimental studies
- Military and Defense Studies
- Quantum Chromodynamics and Particle Interactions
- Metalloenzymes and iron-sulfur proteins
- Metal complexes synthesis and properties
- Hybrid Renewable Energy Systems
- Electrocatalysts for Energy Conversion
- Distributed and Parallel Computing Systems
- Catalysis and Oxidation Reactions
Yale University
1997-2022
University of Washington
2022
Los Alamos National Laboratory
2012-2021
Los Alamos Medical Center
2010-2020
Loughborough University
2019
Novel (United States)
2018
Thomas Jefferson National Accelerator Facility
2014
Rutherford Appleton Laboratory
1981-2012
Science and Technology Facilities Council
2009-2012
University of Ottawa
2011
A method to regenerate lightweight, hydrogen-rich ammonia borane improves its prospects as a vehicular fuel source.
Abstract Interest in sustainable non‐hydrocarbon‐based fuels for transportation has grown as the realization that supply of fossil is limited and deleterious environmental effects burning them come into public focus. The use hydrogen (H 2 ) been proposed an alternative, but its pure form undesirable due to high pressures or low temperatures required store useful quantities. Approaches ameliorate this issue, which stem from volumetric energy density H , include pursuit sorbents capable...
For years, following the ideas of Shvo and Noyori, core assumption metal–ligand bifunctional molecular catalysis has relied on direct involvement chelating ligand in catalytic reaction via a reversible proton (H+) transfer through cleavage/formation one its X–H bonds (X = O, N, C). A recently revised mechanism Noyori asymmetric hydrogenation (Dub, P. A. et al. J. Am. Chem. Soc. 2014, 136, 3505) suggests that is rather involved stabilization determining transition states N–H···O...
The mechanism of catalytic hydrogenation acetophenone by the chiral complex trans-[RuCl2{(S)-binap}{(S,S)-dpen}] and KO-t-C4H9 in propan-2-ol is revised on basis DFT computations carried out dielectric continuum most recent experimental observations. results these collective studies suggest that neither a six-membered pericyclic transition state nor any multibond concerted states are involved. Instead, hydride moiety transferred an outer-sphere manner to afford ion-pair, corresponding both...
The present article describes the current level of understanding mechanism enantioselective hydrogenation and transfer aromatic ketones with pioneering prototypes bifunctional catalysts, Noyori Noyori–Ikariya complexes.
Going full circle: Ammonia borane is a potential H2-releasing fuel. Polyborazylene, form of the spent fuel, can be regenerated efficiently in one-pot process by stepwise addition appropriate digesting and reducing agents. A unique feature this formation NH3, which retained some digested species. Detailed facts importance to specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted authors. Please...
The GridPP Collaboration is building a UK computing Grid for particle physics, as part of the international effort towards Large Hadron Collider. project, funded by Particle Physics and Astronomy Research Council (PPARC), began in September 2001 completed its first phase 3 years later. collaboration approximately 100 researchers 19 university physics groups, Central Laboratory Councils CERN, reflecting strategic importance project. In with other European US efforts, project demonstrated...
Two mononuclear high-spin Fe(II) complexes with trigonal planar ([Fe(II)(N(TMS)(2))(2)(PCy(3))] (1) and distorted tetrahedral ([Fe(II)(N(TMS)(2))(2)(depe)] (2) geometries are reported (TMS = SiMe(3), Cy cyclohexyl, depe 1,2-bis(diethylphosphino)ethane). The magnetic properties of 1 2 reveal the profound effect out-of-state spin-orbit coupling (SOC) on slow relaxation. Complex exhibits relaxation magnetization under an applied optimal dc field 600 Oe due to presence low-lying electronic...
Ammonia-borane (NH(3)BH(3), AB) has garnered interest as a hydrogen storage material due to its high weight percent content and ease of H(2) release relative metal hydrides. As consequence dehydrogenation, B-N-containing oligomeric/polymeric materials are formed. The ability control this process dictate the identity generated polymer opens up possibility targeted synthesis new materials. While precious metals have been used in regard, construct such using earth-abundant Fe presents more...
In stark contrast to the transition metals, examples of imido or alkylidene complexes lanthanides remain scarce. A recent literature survey reveals that only nine lanthanide have been reported, and majority these arisen serendipitously. Concrete species containing lanthanide–carbon multiple bonds are even more sparse. Recently, some rational approaches synthesis LnX functionalities detailed (X = C, N). Additionally, a DFT (Density Functional Theory) study samarium complex has provided...
Dipicolinate vanadium(V) complexes oxidize lignin model pinacol monomethyl ether (A), 2-phenoxyethanol (B), 1-phenyl-2-phenoxyethanol (C), and 1,2-diphenyl-2-methoxyethanol (D). With substrates having C−H bonds adjacent to the alcohol moiety (B−D), bond is broken in pyridine-d5 solvent, yielding 2-phenoxyacetaldehyde from B, 2-phenoxyacetophenone C, benzoin methyl D. In DMSO-d6 solvent reaction slower, both C−C cleavage products are observed for The vanadium(IV) of these reactions have been...
Understanding the bonding trends within, and differences between, 4f 5f element series with soft donor atom ligands will aid elucidation of fundamental origins actinide (An) versus lanthanide (Ln) selectivity that is integral to many advanced nuclear fuel cycle separation concepts. One principal obstacles acquiring such knowledge dearth well characterized transuranic molecules prevents necessary comparison coordination chemistry, electronic structure, bonding. Reported herein new chemistry...
Molecular metal/NH bifunctional Noyori-type catalysts are remarkable in that they among the most efficient artificial developed to date for hydrogenation of carbonyl functionalities (loadings up ∼10–5 mol %). In addition, these typically exhibit high C═O/C═C chemo- and enantioselectivities. This unique set properties is traditionally associated with operation an unconventional mechanism homogeneous which chelating ligand plays a key role facilitating catalytic reaction enabling...
The reactivity of vanadium complexes bearing the ligand dipicolinic acid (H2dipic) with alcohols has been explored. Dipic are able to catalyze aerobic oxidative C−C bond cleavage pinacol. Reaction under anaerobic conditions allowed for isolation a VIII μ-oxo dimer, supporting involvement in oxidation reactions. Stoichiometric unactivated aliphatic also observed, cyclobutanol producing cyclobutanone 93% yield. absence ring-opening products this reaction provides further support intermediates.
Relatively recent developments in metalloenzyme and organometallic chemistry have targeted a growing link between these outwardly incongruous fields, giving birth to merger now popularly termed "bio-organometallic" chemistry. The astonishing discovery of CO CN ligands bound dinuclear iron sites billion-year-old hydrogenase enzymes has led new paradigm triggered an explosion research on bioinspired article will focus the impressive array principles that work concert structure function H2ases....
In this review we detail recent developments in the synthesis of lanthanoid complexes (group III and lanthanide elements) containing multiple bonding interactions with tetrel, pnictogen chalcogen main group elements.
A shift to the hydrogen economy requires development of an effective fuel carrier with high volumetric and gravimetric storage capacity. Ammonia borane (AB) has emerged as a leading candidate due its light weight multiple protic (N–H) hydridic (B–H) hydrogens. As consequence, much work been directed towards fine tuning release H2 from AB, in addition regeneration dehydrogenated "spent fuel" materials. This review summarizes these methodologies.
Abstract The catalytic hydroboration of ketones, aldehydes, and imines with pinacol borane Ni(bpy)(cod) has been demonstrated in benzene at room temperature low catalyst loadings (0.03–0.3 mol‐%). Spectroscopic structural evidence support the formulation as containing a Ni I cation bpy · – ligand. complex reacts quickly ketonic substrates to form an adduct that appears function entryway into activity.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, Properties, and X-ray Structures of the Lanthanide .eta.6-Arene-Bridged Aryloxide Dimers Ln2(O-2,6-i-Pr2C6H3)6 Their Lewis Base Adducts Ln(O-2,6-i-Pr2C6H3)3(THF)2 (Ln = Pr, Nd, Sm, Gd, Er, Yb, Lu)David M. Barnhart, David L. Clark, John C. Gordon, Huffman, Rebecca Vincent, G. Watkin, Bill D. ZwickCite this: Inorg. Chem. 1994, 33, 16, 3487–3497Publication Date (Print):August 1, 1994Publication History Published online1 May 2002Published...
Dipicolinate vanadium(V) alkoxide complexes (dipic)VV(O)(OR) (OR = isopropoxide (1), n-butanoxide (2), cyclobutanoxide (3), and α-tert-butylbenzylalkoxide (4)) react with pyridine to afford vanadium(IV) 0.5 equiv of an aldehyde or ketone product. The role in the reaction has been investigated. Both NMR X-ray crystallography experiments indicate that coordinates 1, which is equilibrium (dipic)VV(O)(OiPr)(pyr) (1-Pyr). Kinetic studies alcohol oxidation suggest a pathway where rate-limiting...
The start-up of the Large Hadron Collider (LHC) at CERN, Geneva, presents a huge challenge in processing and analysing vast amounts scientific data that will be produced. architecture worldwide grid handle 15 PB particle physics annually from this machine is based on hierarchical tiered structure. We describe development UK component (GridPP) prototype system to full exploitation for real analysis. This includes physical infrastructure, deployment middleware, operational experience initial...
Abstract Interest in developing renewable fuels is continuing to grow and biomass represents a viable source of carbon with which replace fossil‐based components transportation fuels. During our own work, we noticed that chemists think terms functional groups whereas fuel engineers physical properties. In this Concept article, discuss the effect oxygen on potential This serves as way informing thinking provides us basis design synthesize molecules from could provide useful