Author: Eric Arn MaataPublisher:
ISBN:
Category : Molybdenum
Languages : en
Pages : 416
Book Description
Alkyne and Imido Molybdenum Complexes and Their Relationship to Nitrogenase
Author: Eric Arn MaataPublisher:
ISBN:
Category : Molybdenum
Languages : en
Pages : 416
Book Description
Spectroscopic Studies of Molybdenum Complexes as Models for Nitrogenase
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Because biological nitrogen fixation requires Mo, there is an interest in inorganic Mo complexes which mimic the reactions of nitrogen-fixing enzymes. Two such complexes are the dimer Mo2O4 (cysteine)2/sup 2 -/ and trans-Mo(N2)2(dppe)2 (dppe = 1,2-bis(diphenylphosphino)ethane). The H1 and C13 NMR of solutions of Mo2O4(cys)2/sup 2 -/ are described. It is shown that in aqueous solution the cysteine ligands assume at least three distinct configurations. A step-wise dissociation of the cysteine ligand is proposed to explain the data. The Extended X-ray Absorption Fine Structure (EXAFS) of trans-Mo(N2)2(dppe)2 is described and compared to the EXAFS of MoH4(dppe)2. The spectra are fitted to amplitude and phase parameters developed at Bell Laboratories. On the basis of this analysis, one can determine (1) that the dinitrogen complex contains nitrogen and the hydride complex does not and (2) the correct Mo-N distance. This is significant because the Mo inn both complexes is coordinated by four P atoms which dominate the EXAFS. A similar sort of interference is present in nitrogenase due to S coordination of the Mo in the enzyme. This model experiment indicates that, given adequate signal to noise ratios, the presence or absence of dinitrogen coordination to Mo in the enzyme may be determined by EXAFS using existing data analysis techniques. A new reaction between Mo2O4(cys)2/sup 2 -/ and acetylene is described to the extent it is presently understood. A strong EPR signal is observed, suggesting the production of stable Mo(V) monomers. EXAFS studies support this suggestion. The Mo K-edge is described. The edge data suggests Mo(VI) is also produced in the reaction. Ultraviolet spectra suggest that cysteine is released in the course of the reaction.
Molybdenum Complexes as Models of Nitrogenase
Author: Michael A. JacksonNitrido- and Imido-complexes of Molybdenum(V)
Author: Mark E. NoblePublisher:
ISBN:
Category : Molybdenum compounds
Languages : en
Pages : 360
Book Description
American Doctoral Dissertations
Author: Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 704
Book Description
Dissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 572
Book Description
Ligand Variation in Molybdenum Imido Alkylidene Complexes
Author: Alejandro Gaston LichtscheidlPublisher:
ISBN:
Category :
Languages : en
Pages : 222
Book Description
Chapter 1. A general introduction is given. Chapter 2. The biscarboxylate species, Mo(NR)(CHCMe 2Ph)(O 2CPh3)2 (R = 2,6-i-Pr2C6H3, 2,6- Me2C6H3, 2-t-BuC 6H4, or 1 -adamantyl) are compared to newly synthesized bis(terphenylcarboxylate) species, Mo(NR)(CHCMe 2Ph)(O 2CTer)2 (Ter = 2,6-diphenyl-4- methylphenyl or 2,6-diphenyl-4-methoxyphenyl). Preparation of bis(terphenylcarboxylate) species was accomplished through protonolysis of Mo(NR)(CHCMe2R')(Me2Pyr)2 with two equivalents of TerCO2H and one of them was characterized through X-ray crystallography. Photolysis experiments of many of the biscarboxylate complexes led to rate constants for the converstion of anti to syn species, which are much slower than bisalkoxide species. Trimethylphosphine adducts of selected triphenylacetate complexes have been isolated and studied in solution. Protonolysis of Mo(NAr)(CHCMe 2R')(Me 2Pyr)2 (Ar = 2,6-i-Pr 2C6H3) with one equivalent of TerCO2H led to the isolation of a handful of monocarboxylate species, Mo(NAr)(CHCMe 2Ph)(O 2CAr')(Me2Pyr). An X-ray structure of one of them was also characterized. Several of the bis(triphenylacetate) complexes and all of the monocarboxylates are active initiators for the regioselective polymerization of diethyl dipropargylmalonate (DEPDM). In the case of the latter compounds, activity towards olefins is also observed and briefly mentioned.
Comprehensive Dissertation Index
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 992
Book Description
The Synthesis and Reactions of Molybdenum(II) and Tungsten(II) Alkyne Complexes
Author: Elaine M. ArmstrongThe Redox Chemistry of Molybdenum and Tungsten Alkyne Complexes
Author: Elena Patrkon-RodrkiguezPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description