A5074276957- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Coordination Chemistry and Organometallics
- Asymmetric Synthesis and Catalysis
- Crystallography and molecular interactions
- Synthetic Organic Chemistry Methods
- Oxidative Organic Chemistry Reactions
- Advanced NMR Techniques and Applications
- Organic Chemistry Cycloaddition Reactions
- Organometallic Complex Synthesis and Catalysis
- Asymmetric Hydrogenation and Catalysis
- Fluorine in Organic Chemistry
- Molecular spectroscopy and chirality
- Synthesis and characterization of novel inorganic/organometallic compounds
- NMR spectroscopy and applications
- Chemical Reaction Mechanisms
- Synthesis and Catalytic Reactions
- CO2 Reduction Techniques and Catalysts
- Carbon dioxide utilization in catalysis
- Inorganic and Organometallic Chemistry
- Axial and Atropisomeric Chirality Synthesis
- Cancer Treatment and Pharmacology
- Traditional and Medicinal Uses of Annonaceae
- Analytical Chemistry and Chromatography
- Chemical Synthesis and Analysis
Brown University
2011-2023
Robert Bosch (Germany)
2020
John Brown University
1984-2019
Providence College
2013-2019
University of Massachusetts Dartmouth
2014
Institute for the Chemistry of OrganoMetallic Compounds
2004-2011
University of Bari Aldo Moro
2004-2011
Boston University
2007
The University of Western Australia
2002
Stanford University
2001
Iron/Lewis acid co-catalysts hydrogenate to CO<sub>2</sub>to formate with unprecedented turnover for a first row transition metal catalyst.
We report the synthesis and structure determination of a new Au22 nanocluster coordinated by six bidentate diphosphine ligands: 1,8-bis(diphenylphosphino) octane (L(8) for short). Single crystal X-ray crystallography electrospray ionization mass spectrometry show that cluster assembly is neutral can be formulated as Au22(L(8))6. The core consists two Au11 units clipped together four L(8) ligands, while additional ligands coordinate to each unit in fashion. Eight gold atoms at interface are...
Nuclear magnetic resonance (NMR) is the most powerful and widely utilized technique for determining molecular structure. Although traditional NMR data analysis involves correlation of chemical shift, coupling constant, NOE interactions to specific structural features, a largely overlooked method introduced more than 40 years ago, pulsed gradient spin−echo (PGSE), measures diffusion coefficients molecules in solution, thus providing their relative particle sizes. In early 1990s, PGSE sequence...
Formula weight (FW) information is important to characterize the composition, aggregation number, and solvation state of reactive intermediates organometallic complexes. We describe an internal reference correlated DOSY method for calculating FW unknown species in different solvents with concentrations. Examples both small molecule (DIPA) complex (aggregate 1) yield excellent correlations. also found relative diffusion rate inversely proportional viscosity change solution, which consistent...
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTDiffusion-Ordered NMR Spectroscopy (DOSY) of THF Solvated n-Butyllithium AggregatesIvan Keresztes and Paul G. WilliardView Author Information Department Chemistry, Brown University Providence, Rhode Island, 02912 Cite this: J. Am. Chem. Soc. 2000, 122, 41, 10228–10229Publication Date (Web):September 27, 2000Publication History Received26 June 2000Published online27 September inissue 1 October...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTResolution, asymmetric transformation, and configuration of Troeger's base. Application base as a chiral solvating agentSamuel H. Wilen, Jian Zhong Qi, Paul G. WilliardCite this: J. Org. Chem. 1991, 56, 2, 485–487Publication Date (Print):January 1, 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://pubs.acs.org/doi/10.1021/jo00002a002https://doi.org/10.1021/jo00002a002research-articleACS PublicationsRequest...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolid-state structures of n-butyllithium-TMEDA, -THF, and -DME complexesMichael A. Nichols Paul G. WilliardCite this: J. Am. Chem. Soc. 1993, 115, 4, 1568–1572Publication Date (Print):February 1, 1993Publication History Published online1 May 2002Published inissue 1 February 1993https://pubs.acs.org/doi/10.1021/ja00057a050https://doi.org/10.1021/ja00057a050research-articleACS PublicationsRequest reuse permissionsArticle...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTX-ray crystal structures of lithium, sodium, and potassium enolates pinacolonePaul G. Williard Gene B. CarpenterCite this: J. Am. Chem. Soc. 1986, 108, 3, 462–468Publication Date (Print):February 1, 1986Publication History Published online1 May 2002Published inissue 1 February 1986https://pubs.acs.org/doi/10.1021/ja00263a016https://doi.org/10.1021/ja00263a016research-articleACS PublicationsRequest reuse permissionsArticle...
We report the synthesis and structure determination of a new Au20 nanocluster coordinated by four tripodal tetraphosphine (PP3) ligands {PP3 = tris[2-(diphenylphosphino)ethyl]phosphine}. Single-crystal X-ray crystallography electrospray ionization mass spectrometry show that cluster assembly can be formulated as [Au20(PP3)4]Cl4. The consists an icosahedral Au13 core seven-Au-atom partial outer shell arranged in local C3 symmetry. One PP3 ligand coordinates to Au atoms shell, while other...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure and reactivity of lithium diisopropylamide in the presence N,N,N',N'-tetramethylethylenediamineMax P. Bernstein, Floyd E. Romesberg, David J. Fuller, Aidan T. Harrison, B. Collum, Qi Yong Liu, Paul G. WilliardCite this: Am. Chem. Soc. 1992, 114, 13, 5100–5110Publication Date (Print):June 1, 1992Publication History Published online1 May 2002Published inissue 1 June...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe first structural characterization of a dimeric lithium ketone enolate-LDA complexPaul G. Williard and Mark J. HintzeCite this: Am. Chem. Soc. 1987, 109, 18, 5539–5541Publication Date (Print):September 1, 1987Publication History Published online1 May 2002Published inissue 1 September 1987https://pubs.acs.org/doi/10.1021/ja00252a048https://doi.org/10.1021/ja00252a048research-articleACS PublicationsRequest reuse permissionsArticle...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAggregated intermediates in the aldol reaction sequence. Crystal structure of open dimer LiTMP.cntdot.TMEDAPaul G. Williard and Qi Yong LiuCite this: J. Am. Chem. Soc. 1993, 115, 8, 3380–3381Publication Date (Print):April 1, 1993Publication History Published online1 May 2002Published inissue 1 April 1993https://pubs.acs.org/doi/10.1021/ja00061a067https://doi.org/10.1021/ja00061a067research-articleACS PublicationsRequest reuse permissionsArticle...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAsymmetric induction in the vinylogous amide photocycloaddition reaction. A formal synthesis of vindorosineJeffrey D. Winkler, Robert Scott, and Paul G. WilliardCite this: J. Am. Chem. Soc. 1990, 112, 24, 8971–8975Publication Date (Print):November 1, 1990Publication History Published online1 May 2002Published inissue 1 November 1990https://doi.org/10.1021/ja00180a049RIGHTS & PERMISSIONSArticle Views1426Altmetric-Citations85LEARN ABOUT THESE...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure and reactivity of lithium diisopropylamide (LDA) in hydrocarbon solutions. Formation unsolvated ketone, ester, carboxamide enolatesYong Joo Kim, Max P. Bernstein, Angela S. Galiano Roth, Floyd E. Romesberg, Paul G. Williard, David J. Fuller, Aidan T. Harrison, B. CollumCite this: Org. Chem. 1991, 56, 14, 4435–4439Publication Date (Print):July 1, 1991Publication History Published online1 May 2002Published inissue 1 July...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTX-ray crystal structure of an unsolvated lithium enolate anionPaul G. Williard and Gene B. CarpenterCite this: J. Am. Chem. Soc. 1985, 107, 11, 3345–3346Publication Date (Print):May 1, 1985Publication History Published online1 May 2002Published inissue 1 1985https://pubs.acs.org/doi/10.1021/ja00297a049https://doi.org/10.1021/ja00297a049research-articleACS PublicationsRequest reuse permissionsArticle Views332Altmetric-Citations82LEARN ABOUT THESE...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudies on the synthesis of vitamin B12. 4Robert V. Stevens, Normand. Beaulieu, Wing Hong. Chan, Andrej R. Daniewski, Takeshi. Takeda, Adrian. Waldner, Paul G. Williard, and Ulrich. ZutterCite this: J. Am. Chem. Soc. 1986, 108, 5, 1039–1049Publication Date (Print):March 1, 1986Publication History Published online1 May 2002Published inissue 1 March 1986https://pubs.acs.org/doi/10.1021/ja00265a033https://doi.org/10.1021/ja00265a033research-articleACS...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAddition of Grignard reagents and ketone enolates to the arene in (arene)manganese tricarbonyl cationsYoung Keun Chung, Paul G. Williard, Dwight A. SweigartCite this: Organometallics 1982, 1, 8, 1053–1056Publication Date (Print):August 1982Publication History Published online1 May 2002Published inissue 1 August 1982https://pubs.acs.org/doi/10.1021/om00068a009https://doi.org/10.1021/om00068a009research-articleACS PublicationsRequest reuse...
Polyomaviruses are ubiquitous pathogens that cause severe disease in immunocompromised individuals. JC polyomavirus (JCPyV) is the causative agent of fatal demyelinating progressive multifocal leukoencephalopathy (PML), whereas BK (BKPyV) causes polyomavirus-induced nephropathy and hemorrhagic cystitis. Vaccines or antiviral therapies targeting these viruses do not exist, treatments focus on reducing underlying immunosuppression. We demonstrate retro-2(cycl), an inhibitor ricin Shiga-like...
The Lewis acid tris(pentafluorophenyl)borane was found to rapidly promote ring-opening β-hydride elimination in a 1,1′-bis(diphenylphosphino)ferrocene (dppf) nickelalactone complex under ambient conditions. thermodynamic product of characterized as (dppf)Ni(CH(CH3)CO2BArf3), the result and subsequent 2,1-insertion from transient nickel(II) acrylate hydride intermediate. Treatment (dppf)Ni(CH(CH3)CO2BArf3) with nitrogen-containing base afforded diphosphine nickel(0) η2-acryl borate adduct....
The catalytic conversion of carbon dioxide and olefins into acrylates has been a long standing target, because society attempts to synthesize commodity chemicals in more economical sustainable fashion. Although nickel complexes have known successfully couple CO2 ethylene for decades, key β-hydride elimination step proven major obstacle the development process. Recent studies shown that Lewis acid additives can be used create lower-energy pathway facilitate low number turnovers. However,...
Aggregates consisting of lithium halides with either amides or enolates have been characterized by X-ray crystallography. Two structural types, solvated heterodimers and heterotrimers, found for halide/amide combinations. compounds containing both halide enolate also identified as heterodimers. Using this information, we propose a reaction sequence enolization subsequent aldol addition involving halide-containing aggregates. An ab initio PM3 theoretical study model systems shows that between...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMixed aggregates: crystal structures of a lithium ketone enolate/lithium amide and sodium ester enolate/sodium amidePaul G. Williard Mark J. HintzeCite this: Am. Chem. Soc. 1990, 112, 23, 8602–8604Publication Date (Print):November 1, 1990Publication History Published online1 May 2002Published inissue 1 November 1990https://pubs.acs.org/doi/10.1021/ja00179a066https://doi.org/10.1021/ja00179a066research-articleACS PublicationsRequest reuse...
13C INEPT Diffusion-ordered NMR spectroscopy (DOSY) with an internal reference system was developed to study the aggregation state of THF-solvated LDA dimeric complex. Six components are clearly identified in diffusion dimension, and their DOSY-generated spectrum slices agree extremely well respective spectra. The correlation between log D FW linear least-squares fit points all is exceptionally high: (r = 0.9985).
The Hg-bridged (PNP)Ni-complex acts as a synthon for Ni(<sc>i</sc>) and homolytically cleaves H<sub>2</sub> to yield [(PNP)NiH].