Structure of tetraethylammonium bromide–succinimide (1/2)

Elding-Pontén, Margareta

doi:10.1107/s010827019300455x

Cited by 2 publications

(2 citation statements)

References 5 publications

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“…Cambridge Structural Database and Receptor Conformation. The Cambridge Structural Database (CSD) gave few examples of structurally characterized N−H···Br - interactions ( d H···Br < 2.8 Å), between a bromide ion and a neutral organic compound . In contrast, many examples were found where the organic species is positively charged and the Br - acts as a counterion.…”

Section: Resultsmentioning

confidence: 99%

Hydrogen Bonding in Anion Recognition: A Family of Versatile, Nonpreorganized Neutral and Acyclic Receptors

1999

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The diamides and disulfonamides m-C(6)H(4)(CONHAr)(2) (Ar = Ph, 1; p-n-BuC(6)H(4), 2, 2,4,6-Me(3)C(6)H(2), 3), m-C(6)H(4)(SO(2)NHPh)(2), 4, and 2,6-C(6)H(3)N(CONHPh)(2), 5, readily synthesized on a multigram scale, bind strongly to halides and acetate in organic solvents with K(a)'s as high as 6.1 x 10(4) (NMR spectroscopy). The binding stoichiometry is 1:1 in solution for all cases except for the 4.F(-) and 4.OAc(-) complexes, where both 1:1 and 1:2 binding stoichiometries were found. The association constants in CD(2)Cl(2) ((1)H NMR) follow the trend Cl(-) > Br(-) > I(-) for all the receptors. F(-) and OAc(-) binding may be stronger or weaker than Cl(-) depending on the nature of the receptor. The presence of the pyridine nitrogen in 5 and of the more rigid amide in 1-3 and 5 vs the less rigid sulfonamide structure in 4 increases selectivity for smaller anions. The enthalpy and entropy of formation for 2.Cl(-) were DeltaH = -31 kJ/mol; DeltaS = -23 J/(mol.K) (VT-NMR). The X-ray structure of [PPh(4)](2)[1.Br][Br].CH(2)Cl(2), shows 1:1 complexation of Br(-) via two N-H.Br(-) hydrogen bonds and a syn-syn nonplanar binding conformation for 1. Solution hydrogen bonding was confirmed by FT-IR and NMR spectroscopy. The receptor conformation changes on complexation. Trends in structure/binding relationships show receptor flexibility is an important factor in anion recognition.

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Section: Resultsmentioning

confidence: 99%

Hydrogen Bonding in Anion Recognition: A Family of Versatile, Nonpreorganized Neutral and Acyclic Receptors

1999

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“…Binding is the result of strong N−H···Hal - hydrogen bonding seen in solution by FT-IR and 1 H-NMR spectroscopy and in the solid state by X-ray diffraction. Few structurally characterized N−H···Br - bonds ( d (H···Br) < 2.8 Å) have been reported , for neutral organic compounds but N−H···Cl - examples are more common. We now report the crystal structure of the bromide adduct of the isophthalamide receptor 1 and the halide ion solution binding properties of the more soluble analogue 2 .…”

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confidence: 99%