3,783 research outputs found
Regioselective Intermolecular Coupling Reaction of Arylketones and Alkenes Involving C-H Bond Activation Catalyzed by an \u3cem\u3ein Situ\u3c/em\u3e Formed Cationic Ruthenium-Hydride Complex
The cationic ruthenium hydride complex, formed in situ from the treatment of the tetranuclear ruthenium hydride complex {[(PCy3)(CO)RuH]4(μ4-O)(μ3-OH)(μ2-OH)} with HBF4·OEt2, was found to be a highly effective catalyst for the intermolecular coupling reaction of arylketones and 1-alkenes to give the substituted indene and ortho-C−H insertion products. The formation of the indene products resulted from the initial alkene isomerization followed by regioselective ortho-C−H insertion of 2-alkene and dehydrative cyclization. The preliminary mechanistic studies revealed a rapid and reversible ortho-C−H bond activation followed by the rate-limiting C−C bond formation step for the coupling reaction
Efficient Dehydrogenation of Amines and Carbonyl Compounds Catalyzed by a Tetranuclear Ruthenium-μ-oxo-μ-hydroxo-hydride Complex
The tetranuclear ruthenium-μ-oxo-μ-hydroxo-hydride complex {[(PCy3)(CO)RuH]4(μ4-O)(μ3-OH)(μ2-OH)} (1) was found to be a highly effective catalyst for the transfer dehydrogenation of amines and carbonyl compounds. For example, the initial turnover rate of the dehydrogenation of 2-methylindoline was measured to be 1.9 s−1 with a TON of 7950 after 1 h at 200 °C. The extensive H/D scrambling patterns observed from the dehydrogenation reaction of indoline-N-d1 and indoline-α-d2 suggest a monohydride mechanistic pathway with the C−H bond activation rate-limiting step
Chain-Selective and Regioselective Ethylene and Styrene Dimerization Reactions Catalyzed by a Well-Defined Cationic Ruthenium-Hydride Complex: New Insights on the Styrene Dimerization Mechanism
The cationic ruthenium hydride complex [(η6-C6H6)(PCy3)(CO)RuH]+BF4− was found to be a highly regioselective catalyst for the ethylene dimerization reaction to give 2-butene products (TOF = 1910 h−1, \u3e95% selectivity for 2-butenes). The dimerization of styrene exclusively produced the head-to-tail dimer (E)-PhCH(CH3)CH═CHPh at an initial turnover rate of 2300 h−1. A rapid and extensive H/D exchange between the vinyl hydrogens of styrene-d8 and 4-methoxystyrene was observed within 10 min without forming the dimer products at room temperature. The inverse deuterium isotope effect of kH/kD = 0.77 ± 0.10 was measured from the first-order plots on the dimerization reaction of styrene and styrene-d8 in chlorobenzene at 70 °C. The pronounced carbon isotope effect on both vinyl carbons of styrene as measured by using Singleton’s method (13C(recovered)/13C(virgin) at C1 = 1.096 and C2 = 1.042) indicates that the C−C bond formation is the rate-limiting step for the dimerization reaction. The Eyring plot of the dimerization of styrene in the temperature range of 50−90 °C led to ΔH⧧ = 3.3(6) kcal/mol and ΔS⧧ = −35.5(7) eu. An electrophilic addition mechanism has been proposed for the dimerization of styrene
Intermolecular Dehydrative Coupling Reaction of Arylketones with Cyclic Alkenes Catalyzed by a Well-Defined Cationic Ruthenium-Hydride Complex: A Novel Ketone Olefination Method via Vinyl C–H Bond Activation
The cationic ruthenium−hydride complex [(η6-C6H6)(PCy3)(CO)RuH]+BF4− was found to be a highly effective catalyst for the intermolecular olefination reaction of aryl ketones with cycloalkenes. The preliminary mechanistic analysis revealed that an electrophilic ruthenium−vinyl complex is the key species for mediating both vinyl C−H bond activation and the dehydrative olefination steps of the coupling reaction
Scaling laws for molecular communication
In this paper, we investigate information-theoretic scaling laws, independent
from communication strategies, for point-to-point molecular communication,
where it sends/receives information-encoded molecules between nanomachines.
Since the Shannon capacity for this is still an open problem, we first derive
an asymptotic order in a single coordinate, i.e., i) scaling time with constant
number of molecules and ii) scaling molecules with constant time . For a
single coordinate case, we show that the asymptotic scaling is logarithmic in
either coordinate, i.e., and , respectively.
We also study asymptotic behavior of scaling in both time and molecules and
show that, if molecules and time are proportional to each other, then the
asymptotic scaling is linear, i.e., .Comment: Accepted for publication in the 2014 IEEE International Symposium on
Information Theor
Aqueous Phase C-H Bond Oxidation Reaction of Arylalkanes Catalyzed by a Water-Soluble Cationic Ru(III) Complex [(pymox-Me\u3csub\u3e2\u3c/sub\u3e)\u3csub\u3e2\u3c/sub\u3eRuCl\u3csub\u3e2\u3c/sub\u3e]\u3csup\u3e+\u3c/sup\u3eBF\u3csub\u3e4\u3c/sub\u3e\u3csup\u3e-\u3c/sup\u3e
The cationic complex [(pymox-Me2)RuCl2]+BF4− was found to be a highly effective catalyst for the C−H bond oxidation reaction of arylalkanes in water. For example, the treatment of ethylbenzene (1.0 mmol) with t-BuOOH (3.0 mmol) and 1.0 mol % of the Ru catalyst in water (3 mL) cleanly produced PhCOCH3 at room temperature. Both a large kinetic isotope effect (kH/kD = 14) and a relatively large Hammett value (ρ = −1.1) suggest a solvent-caged oxygen rebounding mechanism via a Ru(IV)-oxo intermediate species
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