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The complex [{η⁵,κP-C₅Me₄CH₂C₆F₃CF₃-5-P(C₆F₄CF₃-4)-2-CH₂P(C₆F₄CF₃-4)₂}RhCl₂] (2) was formed by dehydrofluorinative carbon–carbon coupling in the reaction between bis{bis(4-trifluoromethyltetrafluorophenyl)phosphino}methane and [(η⁵-C₅Me₅)RhCl(μ-Cl)]₂. The structure of 2 has been determined by single crystal X-ray diffraction and compared to that of the pentafluorophenyl analogue [{η⁵,κP-C₅Me₄CH₂C₆F₄P(C₆F₅)-2-CH₂P(C₆F₅)₂}RhCl₂] (3). The presence of the trifluoromethyl groups, although not affecting the local structure about rhodium, disrupts the packing and consequently the structure of the two complexes is very different. The structure of 2 contains channels about 3-fold axes comprising fluoroaryl cavities separated by aliphatic constrictions arising from hexagonal rings of alternating enantiomers.
The salt 1-(2,3,5,6-tetrafluoropyridyl)-3-benzylimidazolium bromide crystallizes in the non-centrosymmetric space group Pna2₁. The structure arises from π–π stacking between the benzyl and tetrafluoropyridyl groups of the cations and cation–bromide interactions. It is the latter that gives rise to the non-centrosymmetry.
The crystal structure of bis{bis(4-trifluoromethyltetrafluorophenyl)phosphino}-methane 2 determined by single crystal X-ray diffraction comprises pairs of molecules related by an inversion center and possessing short P•••P distances. The molecular structure and the structure of the pairs are similar to those in the crystal structure of bis{bis(pentafluorophenyl)-phosphino}methane, although the packing is different. Comparison with the structures of bis(diphenylphosphino)methane and bis{bis(pentafluorophenyl)phosphine}difluoromethane suggests that intramolecular C–H•••F–C interactions are the most important factor in determining the presence of the short P•••P distances in the crystal structures of bis(diarylphosphino)methanes.
In his seminal work On Floating Bodies I Archimedes of Syracuse provided an explanation of the action of solid bodies on water. Although his thesis immediately benefitted King Heiro II?? and has continued to serve mankind well, it ignores the effect of the interfacial interactions between the solid, water and air (surface tension). These interactions are negligible, or at least are considered negligible, compared to forces arising from the effect of gravity on large bodies. However, as the mass of the body decreases, the surface interactions become increasingly important leading to some unusual and potentially useful phenomena. The understanding and application of these effects is currently driving much fundamental research by physicists, chemical engineers, material scientists, and chemists into surfaces that display extreme propertie...
The molecule (η⁵-pentamethylcyclopentadienyl)(methyldiphenylphosphinite-P)dichlororhodium(III), [(η⁵-C₅Me₅)RhCl₂(PPh₂OMe)], crystallizes in the monoclinic crystal system in space group P2₁/c with unit cell parameters a = 16.056(3) Å, b = 9.4331(18) Å, c = 15.745(3) Å, β = 108.330(4), V = 2263.8(7) ų and Z = 4. There is three-legged piano stool geometry about Rh. The Rh-P distance of 2.278(2) Å is shorter than those of [(η⁵-C₅Me₅)RhCl₂(PPh₂OR)] where R is an aryl group, and longer than those found in [(η⁵-C₅Me₅)RhCl₂{PPh(OR)₂}]. The structure reveals significant distortion of the pentamethylcyclopentadienyl towards ′η³,η²-enyl-ene′ coordination.
The 1:1 π–π stacked co-crystals of naphthalene–octafluoronaphthalene and biphenyl–decafluorobiphenyl were synthesized by manual grinding of arene and perfluoroarene.
NMR studies of reactions between a series of arene ruthenium(II) fluoroarylphosphine complexes and Proton Sponge have revealed the necessary conditions for intramolecular dehydrofluorinative ligand coupling. The complex must be cationic, and the phosphine need have only one fluoroaryl substituent. The reaction is rapid and clean for [(?????-toluene)RuCl(dfppe)]BF???, [(?????-mesitylene)RuCl{(C???F???)???PC???H???SMe}]BF??? and the diastereomer of [(?????-toluene)RuCl{Ph???PC???H???PPh(C???F???N-4)}]BF??? in which the tetrafluoropyridyl substituent is close to the ??6-arene. [(?????-p-cymene)RuCl(dfppe)]BF??? reacts in the presence of Proton Sponge to give a mixture of unidentified compounds. The neutral complex [(?????-toluene)RuCl???{Ph???P(C???F???)}] and the diastereomer of [(?????-toluene)RuCl{Ph???PC???H???PPh(C???F???N-4)}]BF??? ...
The tetrafluoropyridyl substituent of the N-heterocycle carbene ligand 1-(2,3,5,6-tetrafluoropyridyl)-3-benzylimidazolin-2-ylidene has been shown to undergo nucleophilic attack when coordinated to rhodium or silver. For the complex Cp *RhCl ₂{κC-(4-NC ₅F ₄)NC ₃H ₂N(CH ₂C ₆H ₅)} nucleophilic attack occurred at the less activated position, meta to the pyridyl ring nitrogen atom. In contrast, for the silver complex [Ag{κC-(4-NC ₅F ₅)NC ₅H ₅N(CH ₅C ₆H ₅)}] + nucleophilic attack occurred ortho to the pyridyl ring nitrogen atom.
“Piano-stool” complexes of rhodium and iridium activated by fluorinated and non-fluorinated N-heterocyclic carbene (NHC) ligands were shown to be catalysts for racemization in the one-pot chemoenzymic dynamic kinetic resolution (DKR) of secondary alcohols. Excellent conversions and good enantioselectivities were observed for alkyl aryl and dialkyl secondary alcohols.
“Etch and coat” methods, potentially useful for large scale production of superhydrophobic surfaces on metals, have been extended by introduction of a thin 20 nm Au interlayer which allowed thiol surface modifiers to be investigated. Fe, Ti and Zn surfaces modified in this way with a polyfluorothiol generally had lower contact angles, θ, than their silane modified equivalents but were more uniform and reproducible. The higher θ values for silanes appear to be associated with an increased effective roughness that is not seen in the thiol coatings, which follow the underlying surface. For Fe, Ti and Zn, θ increased to a maximum with etching time but then decreased significantly. Electron microscopy of samples etched for long times showed fewer grain boundaries, suggesting that the loss of hydrophobicity was related to reduced roughness. ...
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