A5043495201- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Metal complexes synthesis and properties
- Magnetism in coordination complexes
- Metal-Catalyzed Oxygenation Mechanisms
- Crystallography and molecular interactions
- Metalloenzymes and iron-sulfur proteins
- Organometallic Complex Synthesis and Catalysis
- Porphyrin and Phthalocyanine Chemistry
- Porphyrin Metabolism and Disorders
- Metal-Organic Frameworks: Synthesis and Applications
- Folate and B Vitamins Research
- Ferrocene Chemistry and Applications
- Enzyme Structure and Function
- Lanthanide and Transition Metal Complexes
- Polyoxometalates: Synthesis and Applications
- Machine Learning in Materials Science
- Electrocatalysts for Energy Conversion
- Molecular Sensors and Ion Detection
- Neurological diseases and metabolism
- Inorganic and Organometallic Chemistry
- CO2 Reduction Techniques and Catalysts
- Microbial metabolism and enzyme function
- X-ray Spectroscopy and Fluorescence Analysis
- Cyclopropane Reaction Mechanisms
Hofstra University
2024
University of Delaware
2008-2021
University of Wisconsin–Madison
2001-2008
Ursinus College
2008
National Institutes of Natural Sciences
2006
Okazaki Institute for Integrative Bioscience
2006
Ewha Womans University
2006
University of California, Davis
1998-2004
Harvard University Press
2003
Lawrence Berkeley National Laboratory
1998-2002
L-edge X-ray absorption spectroscopy has been used to study, under a variety of conditions, the electronic structure Ni in Ni−Fe hydrogenases from Desulfovibrio gigas, baculatus, and Pyrococcus furiosus. The status enzyme films for these measurements was monitored by FT-IR spectroscopy. spectra were interpreted ligand field multiplet simulations comparison with data model complexes. spectrum D. gigas "form A" is consistent covalent Ni(III) species. In contrast, all reduced samples exhibited...
The monovalent oxidation state of nickel has received a growing amount attention in recent years, part due to its suggested catalytic role number metalloprotein-mediated transformations. In coordination chemistry, nickel(I) is suitable for reductive activation dioxygen, provided ligands are used that stabilize this less common against disproportionation reactions. Two distinct molecular systems have been explored, which access new nickel–dioxygen structure types, namely, monomeric side-on...
An "end-on" Ni2+-superoxo adduct has been prepared via two independent synthetic routes and its structure ascertained by spectroscopic computational methods. The new type in nickel coordination chemistry is supported resonance Raman EPR features, the former displaying a high frequency nu (O-O) mode (1131 cm-1) consistent with significant superoxo character. oxidizes PPh3 to OPPh3 quantitative yield.
The nickel(I) complex [PhTt(Ad)]Ni(CO) (PhTt(Ad), phenyltris((1-adamantylthio)methyl)borate) reacts with O(2) generating a 1:1 species identified as side-on dioxygen adduct based on its spectroscopic properties supported by DFT computational results and reactivity. Ni EXAFS data are fit to S(3)O(2) coordination environment short Ni-O distances, 1.85 A. brown displays rhombic EPR signal g values of 2.24, 2.19, 2.01. INDO/S-CI computations replicate the features suggest that 2 is [NiO(2)](+)...
Reaction of CH3Co(dmgBF2)2L (dmgBF2 = (difluoroboryl)dimethylglyoximato); L py, PEt3) with 2 equiv [Ni(tmc)]OTf (tmc 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane; OTf- CF3SO3-) gave Co(dmgBF2)2py-, [Ni(tmc)]OTf2, and [Ni(tmc)CH3]OTf in 80% yield. The overall transformation provides the first model for transfer a CH3 group from methylcobalamin to Ni-containing enzyme carbon monoxide dehydrogenase during acetyl coenzyme A synthesis. RRSS−[Ni(tmc)CH3](BAr'4) (BAr'4-...
The syntheses and molecular structures of a series tetrahedral zinc complexes designed to model the active sites in Escherichia coli methionine synthases are reported. [PhTttBu]ZnBr (PhTttBu = phenyltris((tert-butylthio)methyl)borate) was prepared characterized crystallographically provide entry into [S3]ZnX complexes. Metathesis with KSPh yielded phenylthiolato complex, [PhTttBu]Zn(SPh), which represents structural mimic homocysteine ligated form enzyme. Alternatively, [S2N]ZnX (X Br, CH3,...
The preparation of the new S3-, tetrahedral enforcer ligand, PhTtt-Bu- (phenyltris((tert-butylthio)methyl)borate), is reported as Tl(I) salt along with its corresponding [PhTtt-Bu]CoCl and [PhTtt-Bu]NiCl complexes. Each has been characterized by X-ray diffraction. Preliminary reactivity studies demonstrate that a useful synthon for range derivatives.
A series of mononuclear zinc thiolate complexes have been prepared and fully characterized. The reactions the with alkyl halides, leading to halides corresponding thioethers, examined by kinetic methods. In toluene, obey a second-order rate law displaying activation parameters consistent S N 2 attack zinc-bound on carbon electrophile. Intramolecular hydrogen bonding an amide N—H sulfur reduces nucleophilicity consequently, alkylation more than 30-fold at 25°C. H-bonding shows inverse H/D...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPoly(methylthiomethyl)Borates: A New Class of Sulfur-Rich Ligands for Metal IonsPinghua Ge, Brian S. Haggerty, Arnold L. Rheingold, and Charles G. RiordanCite this: J. Am. Chem. Soc. 1994, 116, 18, 8406–8407Publication Date (Print):September 1, 1994Publication History Published online1 May 2002Published inissue 1 September 1994https://pubs.acs.org/doi/10.1021/ja00097a074https://doi.org/10.1021/ja00097a074research-articleACS PublicationsRequest...
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTOrganometallic Cobalt(II) and Nickel(II) Complexes Supported by Thioether Ligation: Unexpected Nickel Alkylation the Borato Ligand Phenyltris((tert-butylthio)methyl)boratePeter J. Schebler, Beaven S. Mandimutsira, Charles G. Riordan, Louise M. Liable-Sands, Christopher D. Incarvito, Arnold L. RheingoldView Author Information Department of Chemistry Biochemistry University Delaware, Newark, Delaware 19716 Cite this: Am. Chem. Soc. 2001, 123,...
The tripeptide, Ac−CysGlyCys−CONH2, is utilized as a ligand to bind Ni in fashion identical that found at the active site of acetyl coenzyme A synthase. Ni−peptide construct suitable metalloligand for preparation larger structures formed via bridging Cys side chains. complexes Ni(CysGlyCys)Ni(dppe) and Ni(CysGlyCys)Ni(depe) serve close structural representations binuclear subcluster, exhibiting electrochemical properties demonstrate facile access reduced mixed valent Ni(II)Ni(I) state, which...
A series of low-coordinate, paramagnetic iron complexes in a tris(thioether) ligand environment have been prepared. Reduction ferrous {[PhTttBu]FeCl}2 [1; PhTttBu = phenyltris((tert-butylthio)methyl)borate] with KC8 the presence PR3 (R Me or Et) yields high-spin, monovalent phosphine [PhTttBu]Fe(PR3) (2). These provide entry into other low-valent derivatives via substitution. Carbonylation led to smooth formation low-spin dicarbonyl [PhTttBu]Fe(CO)2 (3). Alternatively, replacement...
Reaction of the nickel metalloligands [EtN2S2]Ni (EtN2S2, N,N'-diethyl-3,7-diazanonane-1,9-dithiolate) or K2[Ni(phmi)] (phmi, N,N'-1,2-phenylenebis(2-sulfanyl-2-methylpropionamide)) with [Cu(CH3CN)4]BF4 yields polynuclear complexes in which two copper(I) ions are bridged by metalloligands. Alternatively, reaction Cu(I) source, [(PhTttBu)Cu] (PhTttBu, phenyltris((tert-butylthio)methyl)borate), generates discrete binuclear NiCu that may serve as models acetyl coenzyme A synthase active site....
The synthesis and characterization of a series [RTt]2M (RTt- = tetrakis((methylthio)methyl)borate; M Fe, Co, Ni) complexes are reported. Isostructural derivatives the newly synthesized phenyltris((methylthio)methyl)borate (PhTt-) also have been prepared characterized. In each case, ligand provides tridentate, face-capping coordination to divalent metal ion. Fe(II) exhibit spin-crossover behavior both in solution solid state. For [PhTt]2Fe, temperature dependence μeff has mapped between 5 K...
Despite the fact that chemists frequently draw electron density distributions, there are few good methods for measuring this quantity, which has contributed to many longstanding controversies in chemistry. In paper, we report first application of element specific L absorption spectra and "white light" sum rule a series nickel complexes, with wide oxidation state range from NiI NiIV. Nickel edge X-ray spectroscopy is turning out be an excellent quantitative probe 3d-vacancies.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSyntheses, Reactivity and Molecular Structures of RSRS-[Ni(tmc)SC6H5](PF6), RRSS-[Ni(tmc)SC6H5](CF3SO3) RRSS-[Ni(tmc)](CF3SO3) (tmc = 1,4,8,11-Tetramethyl-1,4,8,11-tetraazacyclotetradecane)M. S. Ram, Charles G. Riordan, Robert Ostrander, Arnold L. RheingoldCite this: Inorg. Chem. 1995, 34, 23, 5884–5892Publication Date (Print):November 1, 1995Publication History Published online1 May 2002Published inissue 1 November...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanistic aspects of decarboxylation reactions Group 10 metal formato hydrido tricyclohexylphosphine [(PCy3)2M(H)O2CH] derivativesDonald J. Darensbourg, Philip Wiegreffe, and Charles G. RiordanCite this: Am. Chem. Soc. 1990, 112, 15, 5759–5762Publication Date (Print):July 1, 1990Publication History Published online1 May 2002Published inissue 1 July...
O2 for you: The trans-μ-1,2-peroxo Ni2 dimer 3, a structural motif unknown previously in nickel coordination chemistry, was produced by reaction of the (tmc)nickel(I) precursor 1 with O2. Thermal decomposition 3 CH3CN leads to 2, which atoms hydroxide ligand derive from and hydrocarbon solvent.
A series of binuclear NiNi complexes supported by a single thiolate bridge and containing methylnickel moiety have been prepared fully characterized. The represent structural analogues for the proposed organonickel intermediate in acetyl coenzyme synthase catalytic cycle. Variable temperature 31P NMR spectroscopy was used to examine dynamic behavior bridging interaction two derivatives. Kinetic analyses, independent exchange crossover experiments support an intermolecular mechanism....
Strains of Escherichia coli devoid systems for the active transport galactose (galP mgl) still grow on but at rates that are a function concentration medium: half-maximal growth require more than 2 mM-galactose to be present. Evidence is presented taken up by such strains facilitated diffusion carrier specified umg gene (or highly co-transducible with it) which thus part of, or closely associated with, an enzyme II glucose phosphoenolpyruvate-phosphotransferase system. However, entry does...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMethyl Radical-Initiated DNA Cleavage Facilitated by a Discrete Organometallic ComplexCharles G. Riordan and Ping WeiCite this: J. Am. Chem. Soc. 1994, 116, 5, 2189–2190Publication Date (Print):March 1, 1994Publication History Published online1 May 2002Published inissue 1 March 1994https://pubs.acs.org/doi/10.1021/ja00084a087https://doi.org/10.1021/ja00084a087research-articleACS PublicationsRequest reuse permissionsArticle...
Spectroscopic and density functional theory (DFT) electronic structure computational studies on a binuclear bis-μ-oxo bridged (Ni3+)2 complex, [(PhTttBu)2Ni2(μ-O)2] (1), where (PhTttBu) represents phenyl-tris((tert-butylthio)methyl)borate, are presented discussed. These afford detailed description of the Ni2O2 core in dimers provide insight into possible role thioether ligand formation 1 from Ni1+ precursor by O2 activation. From normal coordinate analysis resonance Raman data, value kNi-O =...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProtonation sites in thiolato iron carbonylates: evidence for an arrested Fe(RS-H) oxidative additionMarcetta Y. Darensbourg, Wen Feng Liaw, and Charles G. RiordanCite this: J. Am. Chem. Soc. 1989, 111, 20, 8051–8052Publication Date (Print):September 1, 1989Publication History Published online1 May 2002Published inissue 1 September 1989https://doi.org/10.1021/ja00202a075RIGHTS & PERMISSIONSArticle Views223Altmetric-Citations39LEARN ABOUT THESE...
The zerovalent nickel complex, (triphos)Ni(PPh3), is quantitatively alkylated by a methylcobaloxime reagent. Independent chemical synthesis confirms the nickel-containing product as cation, [(triphos)NiMe]+. These studies provide small molecule precedent for Ni(0) nucleophile during acetyl coenzyme A synthase (ACS) biocatalysis. That corresponding (triphos)NiCO not substrate reaction provides chemical-based rationale ordered binding of methyl followed CO.