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Title: ELECTROCHEMICAL AND SPECTROSCOPIC PROPERTIES OF EIGHT COORDINATE MOLYBDENUM-SULFUR COMPLEXES.
Creator: SMITH, DORIS A., Florida Atlantic University
Abstract/Description: A series of eight-coordinate complexes of molybdenum with 1, 1-dithio ligands are prepared and characterized by electrochemical and spectroscopic methods. Cyclic voltammetry in acetonitrile and methylene chloride solvents reveals reversible metal-based Mo (VI)/Mo(V) and Mo(V)/Mo(IV) electron transfers. Half-wave potentials are linear functions of electron withdrawing and donating parameters of the ligand substituent groups, but do not correlate with charge transfer, vibrational, or electron...
Show moreA series of eight-coordinate complexes of molybdenum with 1, 1-dithio ligands are prepared and characterized by electrochemical and spectroscopic methods. Cyclic voltammetry in acetonitrile and methylene chloride solvents reveals reversible metal-based Mo (VI)/Mo(V) and Mo(V)/Mo(IV) electron transfers. Half-wave potentials are linear functions of electron withdrawing and donating parameters of the ligand substituent groups, but do not correlate with charge transfer, vibrational, or electron paramagnetic resonance spectral data. A linear relationship does exist between electrochemical half-wave potentials and Mo 3d and S 2p x-ray photoelectron binding energies. The results suggest that ligands control half-wave potentials in these complexes by inductive charge donation to the metal center through bonds not directly involved in the redox process.
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Date Issued: 1981
PURL: http://purl.flvc.org/fcla/dt/14054
Subject Headings: Molybdenum
Format: Document (PDF)

Title: ELECTROCHEMICAL REDUCTION OF A BINUCLEAR DIOXO-BRIDGED MOLYBDENUM(V) COMPLEX WITH ETHYLENEDIAMINETETRAACETATE.
Creator: RENDA, VIRGINIA., Florida Atlantic University
Abstract/Description: The electrochemical reduction of Mo 2O4 (EDTA)^2- is studied at a mercury electrode in pH 7-10 borate and phosphate buffers utilizing the techniques of cyclic voltammetry, chronoamperometry, and controlled potential coulometry. The electrochemical reduction of Mo 204(EDTA)^2- is a four-electron, diffusion controlled process in which the initial step is an irreversible two-electron transfer. The product is a binuclear dioxo-bridged complex of Mo (III) with EDTA. Dependence of the electrode...
Show moreThe electrochemical reduction of Mo 2O4 (EDTA)^2- is studied at a mercury electrode in pH 7-10 borate and phosphate buffers utilizing the techniques of cyclic voltammetry, chronoamperometry, and controlled potential coulometry. The electrochemical reduction of Mo 204(EDTA)^2- is a four-electron, diffusion controlled process in which the initial step is an irreversible two-electron transfer. The product is a binuclear dioxo-bridged complex of Mo (III) with EDTA. Dependence of the electrode reaction mechanism on pH, buffer composition, and sodium ion concentration is studied . These results indicate that a chemical protonation step occurs prior to electrochemical reduction. A treatment of the effect of changes in double layer structure on the protonation reaction is presented.
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Date Issued: 1973
PURL: http://purl.flvc.org/fcla/dt/13600
Subject Headings: Molybdenum
Format: Document (PDF)

Title: ELECTROCHEMICALLY CATALYZED REDUCTION OF ACETYLENE BY A MOLYBDENUM - CYSTEINE COMPLEX.
Creator: LEDWITH, DEBRA ANN, Florida Atlantic University, Schultz, Franklin A., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
Abstract/Description: The binuclear , di-mju-oxo-bridged molybdenum(V)-cysteine complex, Na2Mo2O4(cys)2, is frequently cited as a chemical model for nitrogenase enzyme. Coulometric reduction of Na2Mo2O4(cys)2 at the potential of Mo(V)--> Mo(III) reduction (-1. 35 to -1.50 V vs. SCE) in the presence o£ the nitrogenase substrate, acetylene, produces ethylene and ethane. Reduction of C2H2 does not occur in the absence of the molybdenumcysteine complex. The quantities of C2H4 and C2H6 produced are greater than the...
Show moreThe binuclear , di-mju-oxo-bridged molybdenum(V)-cysteine complex, Na2Mo2O4(cys)2, is frequently cited as a chemical model for nitrogenase enzyme. Coulometric reduction of Na2Mo2O4(cys)2 at the potential of Mo(V)--> Mo(III) reduction (-1. 35 to -1.50 V vs. SCE) in the presence o£ the nitrogenase substrate, acetylene, produces ethylene and ethane. Reduction of C2H2 does not occur in the absence of the molybdenumcysteine complex. The quantities of C2H4 and C2H6 produced are greater than the stoichiometric molybdenum content, hence the reduction is catalytic. Acetylene reduction is accompanied by catalytic hydrogen evolution at the surface of the mercury electrode. The rate of acetylene reduction and product yields vary with pH, applied electrode potential, concentration of Na2Mo2O4(cys)2, and the buffer salt. A mechanism for the catalytic process is proposed, and its relationship to chemical models for nitrogenase enzyme is discussed.
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Date Issued: 1975
PURL: http://purl.flvc.org/fcla/dt/13732
Subject Headings: Acetylene reduction assay, Molybdenum
Format: Document (PDF)

Title: Investigation of the oxygen transfer properties of molybdenum-oxide(Et(2)dtc)(2)(THF)(2)I(2).
Creator: Falzone, Samuel, Florida Atlantic University, Baird, Donald M.
Abstract/Description: Mo2o3 (Et2dtc) 2 (THF) 2I2, readily reduces various oxides. The Mo vio2+2 product of this reaction oxidizes TPP to triphenylphosphine oxide. The transient Mo(iv) species formed in the later reaction rapidly and irreversibly reacts with excess Mo vio2+2 to form the original Mo2 o3 4+ complex. These reactions can be also be coupled to provide catalytic oxygen transfer from PNO to TPP. This catalytic cycle can be monitored using a reverse phase high pressure liquid chromatography method that...
Show moreMo2o3 (Et2dtc) 2 (THF) 2I2, readily reduces various oxides. The Mo vio2+2 product of this reaction oxidizes TPP to triphenylphosphine oxide. The transient Mo(iv) species formed in the later reaction rapidly and irreversibly reacts with excess Mo vio2+2 to form the original Mo2 o3 4+ complex. These reactions can be also be coupled to provide catalytic oxygen transfer from PNO to TPP. This catalytic cycle can be monitored using a reverse phase high pressure liquid chromatography method that will also be discussed. The oxides chosen ranged from pyridine-N-oxide to the biological substrates: diphenylsufoxide, DMSO, nicotinamide-N-oxide, and biotin-S-oxide. Since Mo2o3 (Et2dtc) 2 (THF) 2I2 has the ability to abstract oxygen from these biologically significant substrates, it may result in the reconsideration of the role of Mo(V) complexes in catalytic cycles.
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Date Issued: 1989
PURL: http://purl.flvc.org/fcla/dt/14537
Subject Headings: Molybdenum, Oxidation-reduction reaction
Format: Document (PDF)

Title: ELECTROCATALYTIC REACTIONS OF OXO ANIONS WITH MOLYBDENUM - CATECHOL COMPLEXES.
Creator: LAHR, SUZANNE KAY, Florida Atlantic University, Schultz, Franklin A., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
Abstract/Description: Catalytic reductions of NO2, ClO3, and BrO3 by aqueous molybdenum-catechol complexes at pH 9 are investigated by electrochemical techniques. Binding of substrate to the molybdenum center occurs through the unshared electron pair of the substrate central atom. The molybdenum (V) and - (IV) oxidation states are catalytically active, while Mo(III) is not. A single mechanism for the reaction of Mo(V) with all three substrates is proposed, and a rate expression for this reaction is derived....
Show moreCatalytic reductions of NO2, ClO3, and BrO3 by aqueous molybdenum-catechol complexes at pH 9 are investigated by electrochemical techniques. Binding of substrate to the molybdenum center occurs through the unshared electron pair of the substrate central atom. The molybdenum (V) and - (IV) oxidation states are catalytically active, while Mo(III) is not. A single mechanism for the reaction of Mo(V) with all three substrates is proposed, and a rate expression for this reaction is derived. General features of the Mo (IV) reaction are describec. Nitrous oxide was identified by gas chromatography as a product of the Mo(V) - NO2 reaction.
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Date Issued: 1982
PURL: http://purl.flvc.org/fcla/dt/14118
Subject Headings: Molybdenum--Analysis, Catechol--Analysis
Format: Document (PDF)

Title: ELECTROCHEMICAL AND CHEMICAL REDUCTION OF A DIMERIC MOLYBDENUM(V)- CYSTEINE COMPLEX.
Creator: STEPHENSON, ROBERT FRANK., Florida Atlantic University
Abstract/Description: The reduction of Mo2O4 (cysteine)2^2-, a model complex for molybdenum redox enzymes, was studied using pr e parative and electrochemical techniques. Molybdenum(IV) complexes prepared were Mo2O3(cysteine)^4- and Mo2O3 (cysteine)2^2-. Electrochemical reduction of Mo2O4 (cysteine)2^2- produced the monomeric molybdenum(IV)-cysteine complex. The electrode reaction mechanism was found to be an ECE process and involved two one-electron reduction steps. The intermediate in this process was a Mo(V)/Mo...
Show moreThe reduction of Mo2O4 (cysteine)2^2-, a model complex for molybdenum redox enzymes, was studied using pr e parative and electrochemical techniques. Molybdenum(IV) complexes prepared were Mo2O3(cysteine)^4- and Mo2O3 (cysteine)2^2-. Electrochemical reduction of Mo2O4 (cysteine)2^2- produced the monomeric molybdenum(IV)-cysteine complex. The electrode reaction mechanism was found to be an ECE process and involved two one-electron reduction steps. The intermediate in this process was a Mo(V)/Mo(IV) mixed valence dimer, and its rate of dissociation into Mo(V) and Mo(IV) monomers was 50 sec^-1 at pH 9.2 and 22°C. Mo2O4 (cysteine)2^2- was observed to react with free cysteine at pH 8-10. This reaction was first order in Mo2O4 (cysteine)2^2- and first order in cysteine; the rate constant in pH 9.2 borate buffer was 10.9 ± 1.8 x 10^-3 M^-1 sec^-1 at 22°C. Cysteine was catalytically regenerated in this reaction. The reaction was formulated as a cysteine-catalyzed autooxidation-reduction of Mo2O4 (cysteine)2^2- yielding a molybdenum(IV)-cystine dimer as the product.
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Date Issued: 1971
PURL: http://purl.flvc.org/fcla/dt/13459
Subject Headings: Molybdenum compounds, Tumors--Immunological aspects
Format: Document (PDF)

Title: Dependence of spectroscopic and electrochemical properties of dimolybdenum multiimine complexes on ligand structure.
Creator: Yang, Fengli, Florida Atlantic University, Baird, Donald M.
Abstract/Description: The complexes MoX4(Multiimine)2, where X = Cl, Br, I and Multiimine = dimethyl-bipyridine, bipyridine, phenanthroline, bipyrazine, bipyridazine and bipyrimidine, have been prepared. The product complexes apparently contain non-bridged quadruple molybdenum-molybdenum bonds. Each molybdenum is coordinated to a bidentate diimine and two halogen atoms. An electronic absorption study reveals an important trend that the intensity of the delta-->delta* transition increases with decreasing energy....
Show moreThe complexes MoX4(Multiimine)2, where X = Cl, Br, I and Multiimine = dimethyl-bipyridine, bipyridine, phenanthroline, bipyrazine, bipyridazine and bipyrimidine, have been prepared. The product complexes apparently contain non-bridged quadruple molybdenum-molybdenum bonds. Each molybdenum is coordinated to a bidentate diimine and two halogen atoms. An electronic absorption study reveals an important trend that the intensity of the delta-->delta* transition increases with decreasing energy. This shows the energy of this band is determined by mixing of this transition with a metal-to-ligand charge transfer transition. An EEC type mechanism is proposed for the redox behavior of these compounds on the basis of an electrochemical study and some consistent results are obtained by correlating the oxidation potentials with the delta-->delta* transition energies. Also, fairly good correlations of both the delta-->delta* transition energies and the oxidation potentials with pk(a) of L are obtained.
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Date Issued: 1991
PURL: http://purl.flvc.org/fcla/dt/14724
Subject Headings: Molybdenum, Diffusion bonding (Metals), Ligand binding (Biochemistry)
Format: Document (PDF)

Title: Kinetics and mechanistic studies of molybdenum(2) oxygen(3) (diethyl dtc)(2) (THF)(2) iodine(2).
Creator: Abburi, Chakravarthi., Florida Atlantic University, Baird, Donald M.
Abstract/Description: A study of the kinetic behavior of the oxygen atom transfer reaction of Mo2o3 (Et2dtc)2 (THF) 2I2, (I), with a variety of derivatives of pyridine N-oxides has been performed. The reaction behaves in pseudo-first-order fashion under conditions of excess N-oxide. Plots of kobs vs. [N-oxide] do not give straight lines, while plots of 1/kobs vs. 1/[N-oxide] are linear. The rate constant k is taken as the inverse of the slope of this latter plot. There is a marked dependence of the rate on the...
Show moreA study of the kinetic behavior of the oxygen atom transfer reaction of Mo2o3 (Et2dtc)2 (THF) 2I2, (I), with a variety of derivatives of pyridine N-oxides has been performed. The reaction behaves in pseudo-first-order fashion under conditions of excess N-oxide. Plots of kobs vs. [N-oxide] do not give straight lines, while plots of 1/kobs vs. 1/[N-oxide] are linear. The rate constant k is taken as the inverse of the slope of this latter plot. There is a marked dependence of the rate on the functional group in the 4-position of the pyridine ring with the relative rates -CH3 > -H > -Cl > -CN. The above observations can be used to support a mechanism in which a rapid pre-equilibrium, with a large equilibrium constant, is followed by a rate-determining breaking of the Mo-O-Mo bridge.
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Date Issued: 1992
PURL: http://purl.flvc.org/fcla/dt/14828
Subject Headings: Enzyme kinetics, Molybdenum enzymes, Chemical kinetics
Format: Document (PDF)

Title: Synthesis of new materials containing metal-metal quadruple bonds: Complexes containing 2,2';6'2''-terpyridine, 4'-phenyl-2,2';6'2''-terpyridine, 2,3,5,6-tetrakis(alpha-pryidyl)pyrazine, and 1,3-bis(4-methylimino)isoindoline.
Creator: Hu, Chiwei, Florida Atlantic University, Baird, Donald M., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
Abstract/Description: The presence of multiply bonded dimetal units in materials offers opportunities for tuning properties of solids. Materials containing molybdenum-molybdenum quadruple bonds have recently begun being reported. This thesis reports the products of the reactions of dimethyl sulfide (DMS), acetonitrile (ACN) and acetate complexes, Mo2CI4(DMS)4, Mo2(ACN)10ABF4, and Mo2(0Ac)4 with 2,2';6,2"-terpyridine, 4'-phenyl 2,2';6,2"-terpyridine, 2,3,5,6-tetrakis (alpha-pyridyl) pyrazine and 1,3-bis(4...
Show moreThe presence of multiply bonded dimetal units in materials offers opportunities for tuning properties of solids. Materials containing molybdenum-molybdenum quadruple bonds have recently begun being reported. This thesis reports the products of the reactions of dimethyl sulfide (DMS), acetonitrile (ACN) and acetate complexes, Mo2CI4(DMS)4, Mo2(ACN)10ABF4, and Mo2(0Ac)4 with 2,2';6,2"-terpyridine, 4'-phenyl 2,2';6,2"-terpyridine, 2,3,5,6-tetrakis (alpha-pyridyl) pyrazine and 1,3-bis(4-methylimino)isoindoline. Among these ligands, 2,3,5,6-tetrakis (alpha-pyridyl) pyrazine may lead to linear arrays of metal-metal bonds as well as other ordered structures. 1H-NMR, electronic absorption, and infrared data will be quoted to support any structural assignments.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/15212
Subject Headings: Molybdenum compounds, Metal-metal bonds, Electronic structure
Format: Document (PDF)

Title: Fabrication and characterization of copper/molybdenum coatings on carbon fibers by electrodeposition.
Creator: Maucione, Luke J., Florida Atlantic University, Lipka, Stephen M., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The codeposition of a smooth and uniform coating of copper and molybdenum was successfully achieved on T-650 carbon fiber. The effect of various plating parameters on the electrodeposition of copper and molybdenum such as plating bath chemistry, current density, and pulse frequency were studied. By adjusting the aforementioned variables, qualitative and quantitative analysis was conducted to evaluate the deposit smoothness, uniformity, and wetting characteristics. Qualitative analysis of the...
Show moreThe codeposition of a smooth and uniform coating of copper and molybdenum was successfully achieved on T-650 carbon fiber. The effect of various plating parameters on the electrodeposition of copper and molybdenum such as plating bath chemistry, current density, and pulse frequency were studied. By adjusting the aforementioned variables, qualitative and quantitative analysis was conducted to evaluate the deposit smoothness, uniformity, and wetting characteristics. Qualitative analysis of the deposits were made using scanning electron microscopy and energy dispersive spectroscopy. Quantitative analysis of the deposit coating was conducted using inductively coupled plasma chemical analysis, dewetting tests, X-ray diffraction, transmission electron microscopy, and auger electron spectroscopy. Based on the results, a plating line was designed and constructed for the continuous deposition of copper and molybdenum onto carbon fiber tows.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/15124
Subject Headings: Composite materials, Alloy plating, Metallic composites, Molybdenum alloys
Format: Document (PDF)

Molybdenum (5)	+ -
Molybdenum compounds (2)	+ -
Acetylene reduction assay (1)	+ -
Alloy plating (1)	+ -
Catechol--Analysis (1)	+ -

Chemical kinetics (1)	+ -
Composite materials (1)	+ -
Diffusion bonding (Metals) (1)	+ -
Electronic structure (1)	+ -
Enzyme kinetics (1)	+ -
Ligand binding (Biochemistry) (1)	+ -
Metal-metal bonds (1)	+ -
Metallic composites (1)	+ -
Molybdenum alloys (1)	+ -
Molybdenum enzymes (1)	+ -
Molybdenum--Analysis (1)	+ -
Oxidation-reduction reaction (1)	+ -
Tumors--Immunological aspects (1)	+ -

Florida Atlantic University (10)	+ -
Baird, Donald M. (4)	+ -
Charles E. Schmidt College of Science (3)	+ -
Department of Chemistry and Biochemistry (3)	+ -
Schultz, Franklin A. (2)	+ -

Abburi, Chakravarthi. (1)	+ -
College of Engineering and Computer Science (1)	+ -
Department of Ocean and Mechanical Engineering (1)	+ -
Falzone, Samuel (1)	+ -
Hu, Chiwei (1)	+ -
LAHR, SUZANNE KAY (1)	+ -
LEDWITH, DEBRA ANN (1)	+ -
Lipka, Stephen M. (1)	+ -
Maucione, Luke J. (1)	+ -
RENDA, VIRGINIA. (1)	+ -
SMITH, DORIS A. (1)	+ -
STEPHENSON, ROBERT FRANK. (1)	+ -
Yang, Fengli (1)	+ -

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