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  1. Abstract

    Propylene is a crucial building block to produce many industrial‐scale chemicals including polypropylene. The separation of propylene from propane to reach the high‐purity levels needed for downstream applications is a difficult task due to the close similarities in their physical properties. The olefin/paraffin separation including that involving propylene mainly relies on highly energy‐intensive distillation processes and accounts for nearly 0.3% of the global energy consumption. The utility of a copper complex supported by a fluorinated bis(pyrazolyl)borate is demonstrated to accomplish the separation of propylene from propane repeatedly, under mild conditions with high selectivity. Complete characterization of a rare, copper(I) propylene complex is also reported including the molecular structure.

    Free, publicly-accessible full text available December 16, 2023
  2. Abstract

    A series of DOSY experiments have been carried out to determine the solution stoichiometry of silver(I) 3,5‐bis (trifluoromethyl)pyrazolate species. This compound exists as a trimer in the solid state (n = 3) but in solutions of chlorinated solvents, the DOSY data suggest the presence of a mixture of solvent stabilized monomer (n = 1) and dimer (n = 2) in equilibrium. Different approximations have been used including the Stokes–Einstein and the Stokes–Einstein–Gierer–Wirtz equations. Some methodological problems are discussed.

  3. Abstract

    Purification of C2H4from an C2H4/C2H6mixture is one of the most challenging separation processes, which is achieved mainly through energy‐intensive, cryogenic distillation in industry. Sustainable, non‐distillation methods are highly desired as alternatives. We discovered that the fluorinated bis(pyrazolyl)borate ligand supported copper(I) complex {[(CF3)2Bp]Cu}3has features very desirable in an olefin–paraffin separation material. It binds ethylene exclusively over ethane generating [(CF3)2Bp]Cu(C2H4). This molecular compound exhibits extremely high and record ideal adsorbed solution theory (IAST) C2H4/C2H6gas separation selectivity, affording high purity (>99.5 %) ethylene that can be readily desorbed from separation columns. In‐situ PXRD provides a “live” picture of the reversible conversion between [(CF3)2Bp]Cu(C2H4) and the ethylene‐free sorbent in the solid‐state, driven by the presence or removal of C2H4. Molecular structures of trinuclear {[(CF3)2Bp]Cu}3and mononuclear [(CF3)2Bp]Cu(C2H4) are also presented.

  4. Abstract

    Non‐porous small molecule adsorbents such as {[3,5‐(CF3)2Pz]Cu}3(where Pz=pyrazolate) are an emerging class of materials that display attractive features for ethene−ethane separation. This work examines the chemistry of fluorinated copper(I) pyrazolates {[3,5‐(CF3)2Pz]Cu}3and {[4‐Br‐3,5‐(CF3)2Pz]Cu}3with much larger 1‐butene in both solution and solid state, and reports the isolation of rare 1‐butene complexes of copper(I), {[3,5‐(CF3)2Pz]Cu(H2C=CHC2H5)}2and {[4‐Br‐3,5‐(CF3)2Pz]Cu(H2C=CHC2H5)}2and their structural, spectroscopic, and computational data. The copper−butene adduct formation in solution involves olefin‐induced structural transformation of trinuclear copper(I) pyrazolates to dinuclear mixed‐ligand systems. Remarkably, larger 1‐butene is able to penetrate the dense solid material and to coordinate with copper(I) ions at high molar occupancy. A comparison to analogous ethene and propene complexes of copper(I) is also provided.

  5. Described herein are the synthesis, structure, and photophysics of the iodo-substituted cyclic trinuclear copper( i ) complex, Cu 3 [4-I-3,5-(CF 3 ) 2 Pz] 3 supported by a highly-fluorinated pyrazolate in comparison with its previously reported 4-Br/4-Cl analogues. The crystal structure is stabilised by multiple supramolecular interactions of Cu 3 ⋯I and hydrogen/halogen bonding. The photophysical properties and supramolecular interactions are investigated experimentally/computationally for all three 4-halo complexes vis-à-vis relativistic effects.
    Free, publicly-accessible full text available March 28, 2024
  6. Free, publicly-accessible full text available January 30, 2024
  7. Free, publicly-accessible full text available October 15, 2023
  8. A useful ligand involving three pyridyl donor arms and fluorocarbon substituents surrounding the coordination pocket has been assembled and utilized in coinage metal chemistry. This tris(pyridyl)borate serves as an excellent ligand support for the stabilization of ethylene complexes of copper, silver and gold.
  9. Homoleptic, tetranuclear copper( i ) pyrazolates {[3,5-( t -Bu) 2 Pz]Cu} 4 , {[3-(CF 3 )-5-( t -Bu)Pz]Cu} 4 , and {[4-Br-3,5-( i -Pr) 2 Pz]Cu} 4 are excellent stand-alone catalysts for azide–alkyne cycloaddition reactions (CuAAC). This work demonstrates that a range of pyrazolates, including those with electron donating and electron-withdrawing groups to sterically demanding substituents on the pyrazolyl backbones, can serve as effective ligand supports on tetranuclear copper catalysts. However, in contrast to the tetramers and also highly fluorinated {[3,5-(CF 3 ) 2 Pz]Cu} 3 , trinuclear copper( i ) complexes such as {[3,5-( i -Pr) 2 Pz]Cu} 3 and {[3-(CF 3 )-5-(CH 3 )Pz]Cu} 3 supported by relatively electron rich pyrazolates display poor catalytic activity in CuAAC. The behavior and degree of aggregation of several of these copper( i ) pyrazolates in solution were examined using vapor pressure osmometry. Copper( i ) complexes such as {[3,5-(CF 3 ) 2 Pz]Cu} 3 and {[3-(CF 3 )-5-( t -Bu)Pz]Cu} 4 with electron withdrawing pyrazolates were found to break up in solution to different degrees producing smaller aggregates while those such as {[3,5-( i -Pr) 2 Pz]Cu} 3 and {[3,5-( t -Bu) 2 Pz]Cu} 4 with electron rich pyrazolates remain intact.more »In addition, kinetic experiments were performed to understand the unusual activity of tetranuclear copper( i ) pyrazolate systems.« less