Tri- and tetraprotonated ethane (C2H9(3+) and C2H10(4+)) containing five- and six-coordinate carbons

Triprotonated ethane (C(2)H(9)(3+)) 4 and tetraprotonated ethane (C(2)H(10)(4+)) 6 were found by ab initio MP2/cc-pVTZ calculations as viable energy minima. Their structure has three and four two-electron three-center (2e-3c) bonds, respectively. In contrast, calculations showed no minimum-energy structure on the potential energy surface of pentaprotonated ethane (C(2)H(11)(5+)). Charge-charge repulsion may approach its limit in this case. Sufficient stabilization of polycations by Schmidbaur-type auration with (C(6)H(5))(3)PAu, an isolobal analogue of H(+), should be possible for the preparation of the polyaurate derivatives of poly protonated ethane allowing their structural study.     

Guest-induced asymmetry in a metal-organic porous solid with reversible single-crystal-to-single-crystal structural transformation

A metal-organic honeycomb-like 2D pillared-bilayer open framework has been constructed which shows dynamic sponge-like single-crystal-to-single-crystal transformation upon dehydration and rehydration. The dehydrated acentric nonporous phase transformed to the porous centric phase with the selective adsorbate concomitant with the structural transformation correlated with the single-crystal structure determination.     

N-halosuccinimide/BF3-H2O, efficient electrophilic halogenating systems for aromatics

N-Halosuccinimides (NXS, 1) are efficiently activated in trifluoromethanesulfonic acid and BF(3)-H(2)O, allowing the halogenations of deactivated aromatics. Because BF(3)-H(2)O is more economic, easy to prepare, nonoxidizing, and offers sufficiently high acidity (-H(0) approximately 12, only slightly lower than that of trifluoromethanesulfonic acid), an efficient new electrophilic reagent combination of NXS/BF(3)-H(2)O has been developed. DFT calculations at the B3LYP/6-311++G//B3LYP/6-31G level suggest that protonated N-halosuccinimides undergo further protosolvation at higher acidities to reactive superelectrophilic species capable either in the transfer of X(+) from the protonated forms of NXS to the aromatic substrate or in forming a highly reactive and solvated X(+) which would readily react with the aromatic substrates. Structural aspects of the BF(3)-H(2)O complex have also been investigated.     

Reactions of 5-, 6-, 7-, 8-hydroxyquinolines and 5-hydroxyisoquinoline with benzene and cyclohexane in superacids

Isomeric 5-, 6-, 7-hydroxyquinolines (11-13) and 5-hydroxyisoquinoline (14) gave N,C-diprotonated dications in CF(3)SO(3)H-SbF(5) superacid medium. Compounds 11, 13, 14, and 8-hydroxyquinoline (5) underwent selective ionic hydrogenation with cyclohexane in the presence of aluminum chloride. Compounds 11 and 14 condense with benzene in the presence of aluminum halides. The detailed mechanism of reactions, which involves superelectrophilic dicationic intermediates, is discussed.     

Reaction between [Ru3(CO)10(μ-dppm)] (dppm = Ph2PCH2PPh2) and Te2(C6H4OEt-4)2: X-ray crystal structure of [Ru2(CO)6{μ-C6H4PPh(CH2)PPh}]

Treatment of [Ru₃(CO)₁₀(-dppm)] (1) with the ditelluride Te₂(C₆H₄OEt-4)₂ in refluxing toluene afforded the new aryltellurol bridged complex [Ru₂(CO)₄(-TeC₆H₄OEt-4)₂ (-dppm)] (2) together with three known complexes [Ru₄(CO)₈(-CO)(₄-Te)₂(-dppm)] (3), [Ru₂(CO)₆{-CH₂PPh(C₆H₄)PPh}] (4), and [Ru₂(CO)₆{-C₆H₄PPh(CH₂)PPh}] (5). All the four complexes were characterized by spectroscopic methods, including an X-ray structure determination for 5. Complex 5 crystallizes in the monoclinic space group P2₁/c with a = 13.650(2), b = 9.995(2), c = 18.929(3) Å, = 97.49(2)°, V = 2560.4(8) ų, and Z = 4. In this complex the two ruthenium atoms are bridged by the phosphino-phosphide ligand C₆H₄PPh(CH₂)PPh which is attached to one Ru by the C₆H₄ group and a P atom while to the other Ru by both the two P atoms. Both the ruthenium atoms show distorted octahedral geometry. The Ru—Ru bond length is 2.8719(7) Å.     

Elucidation of the Roles of Ionic Liquid in CO2 Electrochemical Reduction to Value-Added Chemicals and Fuels

The electrochemical reduction of carbon dioxide (CO₂ER) is amongst one the most promising technologies to reduce greenhouse gas emissions since carbon dioxide (CO₂) can be converted to value-added products. Moreover, the possibility of using a renewable source of energy makes this process environmentally compelling. CO₂ER in ionic liquids (ILs) has recently attracted attention due to its unique properties in reducing overpotential and raising faradaic efficiency. The current literature on CO₂ER mainly reports on the effect of structures, physical and chemical interactions, acidity, and the electrode–electrolyte interface region on the reaction mechanism. However, in this work, new insights are presented for the CO₂ER reaction mechanism that are based on the molecular interactions of the ILs and their physicochemical properties. This new insight will open possibilities for the utilization of new types of ionic liquids. Additionally, the roles of anions, cations, and the electrodes in the CO₂ER reactions are also reviewed.     

Amide linkage in novel three-ring bent-core molecular assemblies: polar mesophases and importance of H-bonding

Here, we report the first examples of achiral unsymmetrical three-ring bent-shaped liquid crystals comprising amide and imine linkages with transverse substituents of methyl and chloro moieties on the central phenyl ring in the core, exhibiting polar banana phases. The extensive intra and inter molecular H-bonding induced novel banana mesomorphic phases. One-dimensional stacking in the mesomorphic phase as well as ferroelectric polar order promoted by intermolecular H-bonding of amide linkage is demonstrated. The compounds exhibit multifunctional properties viz., the enantiotropic liquid crystalline (LC) phase at ambient temperatures, electro-optical response, spontaneous polarisation, emission characteristics with large Stokes shift, and even charge distribution with large voltage holding ratio (VHR) values. The smectic type phase was confirmed by XRD studies and polar order was established by switching current and dielectric investigations. DFT studies revealed the importance of their suitability for display applications.     

Analytical/experimental investigation of energy absorption in grid-stiffened composite structures under transverse loading

In this paper we summarize preliminary results from an analytical/experimental study of the energy absorption characteristics of grid-stiffened composite structures under transverse loading. Tests and quasi-static finite element analysis simulations were carried out for isogrid E-glass/polypropylene panels in three-point bending. The results of the tests and simulations show that these types of structures have excellent damage tolerance and that most of the energy absorption occurs beyond initial failure. It is also observed that even though the peak load is greater for loading on the skin side, the specific energy absorption and the range of displacements over which energy is absorbed are significantly better when the load is applied on the rib side.     

Digital speckle correlation for strain measurement by image analysis

This paper is concerned with small strain measurement utilizing the numerical processing of digital images. The proposed method has its theoretical basis in digital signal analysis and, from a methodological point of view, it can be considered as an extension to digital images of the wellknown white light speckle photography technique. That conventional method is based on the analysis of photographic plates that are exposed twice (before and after the specimen deformation) with the image of a random speckle pattern that has been previously printed on the test piece surface. The digital speckle correlation advantages consist of requiring a very simple specimen preparation and, mainly, of allowing the strain field computation just by numerical elaboration of the acquired images. In this paper, the theoretical basis of the technique and some valuable improvements to the known analogous methodologies are presented. Finally, test results for an application of digital speckle correlation are shown and advantages and disadvantages of the technique are elaborated. In addition, further developments in this area are discussed.     

Electronic Structure of Monodithiolated Iron?Oxotungsten Heterometallic Complexes: Integer‐Spin Fe?W Assembly

Fe? W heterometallic complexes, in which an FeX₂ (X=Cl, SPh) moiety is attached to monodithiolene oxotungsten through a sulfide bridge, that is, [Ph₄P]₂[Cl₂Fe(S)₂WOS₂] ( 1 ), [Ph₄P]₂[Cl₂Fe(S)₂WOS₂(DMED)] ( 2 , DMED=dimethylethylenedicarboxylate), [Ph₄P]₂[Cl₂Fe(S)₂WO(tdt)] ( 3 , tdt=toluenedithiolate), [Ph₄P]₂[(SPh)₂Fe(S)₂WO(tdt)] ( 4 ), and [Ph₄P]₂[Cl₂Fe(S)₂WO(edt)] ( 5 , edt=ethanedithiolate), are reported. Mössbauer and EPR spectroscopy, magnetism, electrochemistry, and electronic structural analysis based on DFT and TD‐DFT calculations show the transfer of electron from the iron center to the tungsten center, thus resulting in a ferromagnetically coupled Fe^IIIW^V unit, along with antiferromagnetic intermolecular interactions, from the starting Fe^II and W^VI compounds. A net spin of a S=3 ground state, which arises from ferromagnetically coupled Fe^III and W^V atoms, displays a rare X‐band EPR in normal mode at g≈7 in the solid state.