Direct benzyne-C60 addition does not generate a [5,6] open fulleroid

Recent reports describe the different products resulting from the reaction of C₆₀ with benzyne generated from anthranilic acid derivatives and isoamyl nitrate in the presence and absence of triethylamine. Reinvestigation here via ¹H, ¹³C, HMBC NMR and Mass spectroscopy elucidates that these products are the [6,6] closed C₆₀-fused δ lactones, and not the [5,6] open fulleroids which would result from benzyne addition. Furthermore, theoretical calculations show that the open isomer [5,6] benzyne addition is less stable than the [5,6] closed isomer as an isolable product.     

Towards tetrasilabicyclo[1.1.0]butane: reductive coupling of 1-t-butyl-2,2-dimesityl-1,1,2-trichlorodisilane

Reductive coupling of 1-$\text{t}$-butyl-2,2-dimesityl-1,1,2-trichlorodisilane employing Li-naphthalenide furnishes, on oxygenation or hydrolysis of the reaction mixture, products ($\text{8}$-$\text{11}$) that may arise from insertion of oxygen into or the addition of water across the Si-Si bonds of 1,3-di-$\text{t}$-butyl-2,2,4,4-tetramesityltetrasilabicyclo-[1.1.0]butane ($\text{3}$).     

The cation cluster of heavier group 14 elements: a free germyl cation with trishomoaromaticity

The heavier group 14 element cation cluster compound, [(tBu3Si)6Ge10I]+.TTFPB- (3+. TTFPB-; TTFPB- = tetrakis(2,3,5,6-tetrafluorophenyl)borate), was unexpectedly obtained by thermolysis of in situ prepared iodocyclotrigermene, (tBu3Si)3Ge3I, in toluene in the presence of KI and K+.TTFPB-. The molecular structure of 3+.TTFPB- has been unambiguously determined by X-ray crystallography, showing that 3+ is a free germyl cation. The three "naked" cationic germanium atoms in the framework constitute a three-center two-electron (3c-2e) bond with a trishomocyclotrigermenylium character, which is well-supported by a theoretical calculation on the model compound Ge10H7+.     

Elucidation of hydrodesulfurization mechanism on molybdenum‐based catalysts using 35S radioisotope pulse tracer methods

Elucidation of the hydrodesulfurization (HDS) mechanism on molybdenumbased catalysts using radioisotope tracer methods and reaction kinetics is reviewed. Firstly, to investigate the sulfidation state in Mo/Al₂O₃ and Co–Mo/Al₂O₃ catalysts, presulfiding of these catalysts has been performed using a ³⁵S pulse tracer method. Secondly, HDS of radioactive ³⁵Slabeled dibenzothiophene was carried out over a series of sulfided molybdena–alumina catalysts and cobaltpromoted molybdena–alumina catalysts in a pressurized flow reactor to estimate the behavior of sulfur on the working catalysts. Finally, sulfur exchange of a ³⁵Slabeled catalyst with hydrogen sulfide was performed to estimate the relationship between the amount of labile sulfur and catalytically active sites.     

Elucidation by computer simulations of the CUS regeneration mechanism during HDS over MoS<Subscript>2</Subscript> in combination with <Superscript>35</Superscript>S experiments

The first part of this paper is a short review of the ³⁵S radioactive tracer methods developed in recent years. Then, the experimental results obtained so far on Mo/Al₂O₃ catalysts are compared with computer simulation results recently claimed in order to elucidate the coordinatively unsaturated site (CUS) creation/replenishment/ regeneration mechanism over MoS₂ crystallites. The computer simulations allowed us to pre-select thermodynamically acceptable mechanisms among a set of suggested ones. Then, by comparison of the calculated activation energies with the ³⁵S experiments results we could further validate the most probable mechanism. This mechanism involved the dissociative adsorption of an H₂ molecule on the metallic edge of a MoS₂ crystallite surface with further creation of a CUS by release of one H₂S molecule in the gas phase. Both laboratory and computer simulated experiments permitted to calculate the activation energy for the H2S liberation reaction. In both cases, this energy was about 10- 12 kcal/mol, confirming the accuracy of the proposed mechanism. Moreover, the calculated activation energy of the rate-limiting step for the creation of one CUS by the proposed mechanism was about 23 kcal/mol, which was also in good agreement with the experimental activation energy of the dibenzothiophene (DBT) hydrodesulphurisation (HDS) reaction (typically about 20- 22 kcal/mol). This correlation indicated that the DBT HDS reaction rate might be intrinsically governed by the CUS formation/replenishment process, i.e. that the vacancy formation process is a crucial parameter in the global HDS reaction mechanism. Nevertheless, in the case of the 4,6-dimethyl DBT (4,6-DMDBT) HDS reaction, the experimental activation energy is higher (approx. 30 kcal/mol), confirming that external parameters induced by the 4,6-DMDBT-specific properties themselves are likely to play an important role in the reaction process, in addition to the ones intrinsic to the catalytic phase.     

Further search for the decay K+-->pi(+)nunu;

A search for additional evidence for the rare kaon decay K+-->pi(+)nunu; has been made with a new data set comparable in sensitivity to the previous exposure that produced a single event. No new events were found in the pion momentum region examined, 211pi(+)nunu;) = 1.5(+3.4)(-1.2)x10(-10).     

Reactions of bis[bis(trimethylsilyl)methyl]germylene and the corresponding stannylene with diazidosilanes

The reactions of bis[bis(trimethylsilyl)methyl]-germylene ( 1 ) and the corresponding stannylene ( 2 ) with di-tert-butyldiazidosilane gave N-(azidosilyl)germanimine ( 4 ) and the stannanimine ( 5 ) in quantitative yields. The structures have been confirmed by single-crystal X-ray diffraction. Crystal data for 4 : space group P1 , Z = 2, a = 9.236 (1), b = 12.066 (1), c = 17.068 (1) Å, α = 98.45 (1), β = 90.43, γ = 110.27 (1)°. V = 1761.3 ų, R = 0.051, and Rw = 0.069 based on 4218 reflections with |Fo²| ⩾ 3σ|Fo²|. For 5 : space group P1 , Z = 2, a = 9.183 (1), b = 12.193 (1), c = 17.292 (1) Å, α = 98.74 (1), β = 90.21, γ = 109.96 (1)°, V = 1795.5 ų, R = 0.040, and Rw = 0.051 based on 4795 reflections. The similar reactions of 1 and 2 with 1,3-diazidohexamethyltrisilane ( 16 ) provided azatrisilacyclobutanes quantitatively.     

Exfoliation of Graphite into Graphene in Polar Solvents Mediated by Amphiphilic Hexa‐peri‐hexabenzocoronene

A water‐soluble surfactant consisting of hexa‐peri‐hexabenzocoronene (HBC) as hydrophobic aromatic core and hydrophilic carboxy substituents was synthesized. It exhibited a self‐assembled nanofiber structure in the solid state. Profiting from the π interactions between the large aromatic core of HBC and graphene, the surfactant mediated the exfoliation of graphite into graphene in polar solvents, which was further stabilized by the bulky hydrophilic carboxylic groups. A graphene dispersion with a concentration as high as 1.1 mg L^?1 containing 2–6 multilayer nanosheets was obtained. The lateral size of the graphene sheets was in the range of 100–500 nm based on atomic force microscope (AFM) and transmission electron microscope (TEM) measurements.     

A Fractional Muckenhoupt–Wheeden Theorem and its Consequences

In the 1970s Muckenhoupt and Wheeden made several conjectures relating two weight norm inequalities for the Hardy-Littlewood maximal operator to such inequalities for singular integrals. Using techniques developed for the recent proof of the A ₂ conjecture we prove a related pair of conjectures linking the Riesz potential and the fractional maximal operator. As a consequence we are able to prove a number of sharp one and two weight norm inequalities for the Riesz potential.