Unique "cradled barbell" complex between a secondary diammonium ion and bis(m-phenylene)-32-crown-10.
[formula: see text] The complexation between N,N'-dibenzyl(m-xylylene)diammonium bis(hexafluorophosphate) (2) and bis(m-phenylene)-32-crown-10 (5) was shown to occur in solution by nuclear magnetic resonance with 1:1 stoichiometry and a Ka value of 189 +/- 19 M-1. A crystal structure of 2:5 revealed a unique 1:1 "exo" or "cradled barbell" complex, instead of the expected pseudorotaxane. This unexpected result illustrates that caution be used in interpreting the results from these types of complexes in the solution and "gas" phases on the basis of crystal structures.
Bryant
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Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg 24061, USA.
Guzei
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Rheingold
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Gibson
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D043844:Crown Ethers; D018360:Crystallography, X-Ray; D004988:Ethers, Cyclic / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012997:Solvents
D043844:Crown Ethers; D004988:Ethers, Cyclic; D000644:Quaternary Ammonium Compounds; D012997:Solvents; C410324:bis(m-phenylene)-32-crown-10; D006859:Hydrogen