Synthesis and Decomposition of Alkyl Complexes of Molybdenum(IV) That Contain a [(Me3SiNCH2CH2)3N]3-Ligand. Direct Detection of α-Elimination Processes That Are More than Six Orders of Magnitude Faster than β-Elimination Processes

Schrock, Richard R.; Seidel, Scott W.; Mösch‐Zanetti, Nadia C.; Shih, Keng-Yu; O'Donoghue, Myra B.; Davis, W. M.; Reiff, W. M.

doi:10.1021/ja970697x

Cited by 106 publications

(103 citation statements)

References 48 publications

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“…If this reaction can be achieved cleanly, hydrogen may be generated by ␣-H abstraction, which is a common reaction in organometallic chemistry and is used to generate metal-ligand multiple bonds. For instance, the ␣-H abstraction of metal alkylidenes produces alkylidynes (44). But ␣-H abstraction to produce metal-oxo species, and H 2 is uncommon for well defined hydroxo-hydrido complexes.…”

Section: Methodsmentioning

confidence: 99%

Powering the planet: Chemical challenges in solar energy utilization

Lewis

Nocera

2006

Proc. Natl. Acad. Sci. U.S.A.

7,353

5,492

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Global energy consumption is projected to increase, even in the face of substantial declines in energy intensity, at least 2-fold by midcentury relative to the present because of population and economic growth. This demand could be met, in principle, from fossil energy resources, particularly coal. However, the cumulative nature of CO 2 emissions in the atmosphere demands that holding atmospheric CO 2 levels to even twice their preanthropogenic values by midcentury will require invention, development, and deployment of schemes for carbon-neutral energy production on a scale commensurate with, or larger than, the entire present-day energy supply from all sources combined. Among renewable energy resources, solar energy is by far the largest exploitable resource, providing more energy in 1 hour to the earth than all of the energy consumed by humans in an entire year. In view of the intermittency of insolation, if solar energy is to be a major primary energy source, it must be stored and dispatched on demand to the end user. An especially attractive approach is to store solar-converted energy in the form of chemical bonds, i.e., in a photosynthetic process at a year-round average efficiency significantly higher than current plants or algae, to reduce land-area requirements. Scientific challenges involved with this process include schemes to capture and convert solar energy and then store the energy in the form of chemical bonds, producing oxygen from water and a reduced fuel such as hydrogen, methane, methanol, or other hydrocarbon species.

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Section: Methodsmentioning

confidence: 99%

Powering the planet: Chemical challenges in solar energy utilization

Lewis

Nocera

2006

Proc. Natl. Acad. Sci. U.S.A.

7,353

5,492

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“…From k c = πΔν c /√2 at T c and k c = k B T/h exp(−ΔG ‡ /RT), a ΔG ‡ value of 11.7 kcal/mol was obtained. Values of ΔG ‡ for the C 3 to C 3v conversion in [TMSN 3 N]MoMe and [TMSN 3 N]MoCl were found to be 8.2 ± 0.2 kcal/mol and 9.2 ± 0.2 kcal/mol 19. For Mo N 2 a value of ΔG ‡ = 8.5 ± 0.4 kcal/mol was found; the error is larger since the methylene resonances become relatively broad below T c .…”

Section: Resultsmentioning

confidence: 98%

Molybdenum Triamidoamine Systems. Reactions Involving Dihydrogen Relevant to Catalytic Reduction of Dinitrogen

Hetterscheid

Hanna²,

Schrock³

2009

Inorg. Chem.

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“…Unusual reactions, such as elimination of H 2 from alkyls to give alkylidynes, suggest that the M ≡ C bond (M = Mo or W) is highly favorable in the triamidoamine setting [39,44,45] . However, several problems with TMS substituents were also encountered.…”

Section: Some Characteristics Of Triamidoamine Complexesmentioning

confidence: 99%

“…However, several problems with TMS substituents were also encountered. Examples include migration reactions (e.g., 2.1 [39] ) or CH activation [29,45] …”

Section: Some Characteristics Of Triamidoamine Complexesmentioning

confidence: 99%

“…[Mo(NH3 )]BPh 4 need not be isolated, but can be treated with the hydride reagent immediately. The IR spectrum of MoH features a relatively strong ν (Mo -H) absorption at 1748 cm − 1 (in C 6 D 6 , 1751 cm − 1 in Nujol), shifted by 70 cm − 1 to higher energies relative to that observed in [TMSN 3 N]MoH[45] . MoN 2 ) reacts with dihydrogen slowly (days at 22 ° C in C 6 D 6 ) and reversibly in solution to yield a compound with S = ½ that has the stoichiometry [HIPTN 3 N]Mo(H 2 ) (MoH 2 ).…”

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confidence: 93%

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Catalytic Reduction of Dinitrogen to Ammonia by Molybdenum

Schrock

2010

Catalysis Without Precious Metals

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IntroductionIn the 1960s it was fi rst recognized that dinitrogen is reduced to ammonia in the environment by a metalloenzyme, an FeMo nitrogenase [1 -5] . Although " alternative " nitrogenases have been discovered that do not contain Mo [6 -8] , the FeMo nitrogenase is the most accessible. The FeMo nitrogenase has been purifi ed, crystallized, and studied for several decades. It appears to be the most effi cient at reducing dinitrogen to ammonia, with only approximately one equivalent of dihydrogen being produced 1 -50 atm of dinitrogen. It has also been subjected to X -ray studies that have elicited additional discussion concerning the mechanism of dinitrogen reduction [9 -12] . However, no defi nitive conclusions have yet been reached.After the discovery of the fi rst dinitrogen complex ([Ru(NH 3 ) 5 (N 2 )] 2 + ) by Allen and Senoff [13] , reduction of dinitrogen to ammonia under mild conditions with an abiological catalyst seemed imminent [14 -21] . However, the problem proved to be a great deal more challenging than anticipated. Over a period of several decades, hundreds of man years were invested in attempting to demonstrate that it is possible to reduce dinitrogen abiologically and catalytically under mild conditions (25 ° C and 1 atm of N 2 ). Perhaps it was not fully appreciated how diffi cult reduction of dinitrogen to ammonia in solution with protons and electrons would be; dinitrogen is an extraordinarily stable molecule, and protons are reduced readily to dihydrogen, a reaction that itself may be catalyzed by transition metals. The only reaction in which dinitrogen is reduced catalytically (to an approximately 10 : 1 mixture of hydrazine and ammonia) under mild conditions was reported by Shilov [22] . That reaction also requires molybdenum and is catalytic with respect to it. The solvent is methanol and a relatively strong reducing agent such as sodium amalgam is required. Hydrazine is the primary product with ammonia being formed through a metal -catalyzed disproportionation of hydrazine to dinitrogen and ammonia, a reaction that is accomplished relatively readily by transition metals. Shilov proposed that dinitrogen is bound and reduced between two metal centers, although direct evidence was not provided.

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Synthesis and Decomposition of Alkyl Complexes of Molybdenum(IV) That Contain a [(Me₃SiNCH₂CH₂)₃N]^3-Ligand. Direct Detection of α-Elimination Processes That Are More than Six Orders of Magnitude Faster than β-Elimination Processes

Cited by 106 publications

References 48 publications

Powering the planet: Chemical challenges in solar energy utilization

Powering the planet: Chemical challenges in solar energy utilization

Molybdenum Triamidoamine Systems. Reactions Involving Dihydrogen Relevant to Catalytic Reduction of Dinitrogen

Catalytic Reduction of Dinitrogen to Ammonia by Molybdenum

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