Halogen bonding has increasingly facilitated the assembly of diverse host-guest solids. Here, we show that a well-known class of organic salts, bis(trimethylammonium) alkane diiodides, can reversibly encapsulate alpha,omega-diiodoperfluoroalkanes (DIPFAs) through intermolecular interactions between the host's I- anions and the guest's terminal iodine substituents. The process is highly selective for the fluorocarbon that forms an I-...I(CF2)mI...I- superanion that is matched in length to the chosen dication. DIPFAs that are 2 to 12 carbons in length (common industrial intermediates) can thereby be isolated from mixtures by means of crystallization from solution upon addition of the dissolved size-matched ionic salt. The solid-state salts can also selectively capture the DIPFAs from the vapor phase, yielding the same product formed from solution despite a lack of porosity of the starting lattice structure. Heating liberates the DIPFAs and regenerates the original salt lattice, highlighting the practical potential for the system in separation applications.

Public reporting burden for tris collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information with frequencies that are in excellent agreement with the theoretical calculations for a five-atomic V-shaped ion of C 2 v symmetry. The N 5 ÷Sb 2 Fll" salt was also prepared and its crystal structure was determined. The geometry previously predicted for free gaseous N 5 + from theoretical calculations was confirmed within experimental error. The Sb 2 F 1 r anions exhibit an unusual geometry with eclipsed SbF 4 groups due to inter-ionic bridging with the N 5 ' cations. The N 5 ' cation is a powerful one-electron oxidizer. Its electron affinity falls between 11.0 and 12.08 eV because it readily oxidizes NO to NO ' and NO 2 to NO 2 + but fails to oxidize Xe or 02.

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The highly explosive molecules As(N(3))(3) and Sb(N(3))(3) were obtained in pure form by the reactions of the corresponding fluorides with (CH(3))(3)SiN(3) in SO(2) and purification by sublimation. The crystal structures and (14)N NMR, infrared, and Raman spectra were determined, and the results compared to ab initio second-order perturbation theory calculations. Whereas Sb(N(3))(3) possesses a propeller-shaped, pyramidal structure with perfect C(3) symmetry, the As(N(3))(3) molecule is significantly distorted from C(3) symmetry due to crystal packing effects.

Ab initio molecular orbital theory has been used to calculate accurate enthalpies of formation and adiabatic electron affinities or ionization potentials for N3, N3-, N5+, and N5-from total atomization energies. The calculated heats of formation of the gas-phase molecules/ions at 0 K are ΔHf(N3(2Π)) = 109.2, ΔHf(N3-(1∑+)) = 47.4, ΔHf(N5-(1A1')) = 62.3, and ΔHf(N5+(1A1)) = 353.3 kcal/mol with an estimated error bar of ±1 kcal/mol. For comparison purposes, the error in the calculated bond energy for N2 is 0.72 kcal/mol. Born−Haber cycle calculations, using estimated lattice energies and the adiabatic ionization potentials of the anions and electron affinities of the cations, enable reliable stability predictions for the hypothetical N5+N3-and N5+N5-salts. The calculations show that neither salt can be stabilized and that both should decompose spontaneously into N3 radicals and N2. This conclusion was experimentally confirmed for the N5+N3-salt by low-temperature metathetical reactions between N5SbF6 and alkali metal azides in different solvents, resulting in violent reactions with spontaneous nitrogen evolution. It is emphasized that one needs to use adiabatic ionization potentials and electron affinities instead of vertical potentials and affinities for salt stability predictions when the formed radicals are not vibrationally stable. This is the case for the N5 radicals where the energy difference between vertical and adiabatic potentials amounts to about 100 kcal/mol per N5. Disciplines Chemistry Comments This article is from RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Abstract: Ab initio molecular orbital theory has been used to calculate accurate enthalpies of formation and adiabatic electron affinities or ionization potentials for N3, N3 -, N5 + , and N5 -from total atomization energies. The calculated heats of formation of the gas-phase molecules/ions at 0 K are ∆Hf(N3( 2 Π)) ) 109.2, ∆Hf(N3 -( 1 ∑ + )) ) 47.4, ∆Hf(N5 -( 1 A1′)) ) 62.3, and ∆Hf(N5 + ( 1 A1)) ) 353.3 kcal/mol with an estimated error bar of (1 kcal/mol. For comparison purposes, the error in the calculated bond energy for N2 is 0.72 kcal/mol. Born-Haber cycle calculations, using estimated lattice energies and the adiabatic ionization potentials of the anions and electron affinities of the cations, enable reliable stability predictions for the hypothetical N5 + N3 -and N5 + N5 -salts. The calculations show that neither salt can be stabilized and that both should decompose spontaneously into N3 radicals and N2. This conclusion was experimentally confirmed for the N5 + N3 -salt by low-temperature metathetical reactions between N5SbF6 and alkali metal azides in different solvents, resulting in violent reactions with spontaneous nitrogen evolution. It is emphasized that one needs to use adiabatic ionization potentials and electron affinities instead of vertical potentials and affinities for salt stability predic...

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New fluorinated polyhedral oligomeric silsesquioxane (F-POSS) structures possessing a high degree of hydrophobicity have been prepared via a facile corner-capping methodology.