Structure of molecular and ionic H-bonded complexes of Hexamethylphosphortriamide by low temperature NMR in freon solution

Advances in Molecular Relaxation and Interaction Processes Pub Date : 1982-12-01 DOI:10.1016/0378-4487(82)80055-1

N.S. Golubev, S.F. Bureiko, G.S. Denisov

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引用次数: 5

Abstract

The ¹H NMR spectra have been obtained for a number of H-bonded complexes formed by the interaction of OH-acids of increasing strength and [(CH₃)₂N]₃PO (HMPT) in a freon mixture (CDF₂Cl + CDFCl₂) at 100 K.The signals of the complexes with moderately strong acids (pK_a> −2) are singlets,which proves that they have a molecular structure,AH…B.With stronger acids,a doublet spin-spin coupling of the bridge proton with ³¹P nucleus occurs (J_PH=cca 20 Cps) indicating a complete proton transfer,A⁻…HB⁺.The conclusion has been drawn that a sharp change in structure is caused by gradual change in the interaction energy as measured by ΔpK_a.The spectra of a number of conjugated complexes,[BHB]A⁻,have been taken.If B=B,the homoconjugated cation with a centrosymmetric H-bond is formed,followed by a strong decrease in J_PH.

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氟利昂溶液中六甲基磷三酰胺分子和离子氢键配合物的低温核磁共振结构

在氟利昂混合物(CDF2Cl + CDFCl2)中，在100 K下，得到了强度增加的oh -酸与[(CH3)2N]3PO (HMPT)相互作用形成的若干h键配合物的1H NMR谱。中等强酸配合物(pKa>−2)为单线态，证明它们具有AH…B的分子结构。在较强酸中，桥质子与31P核发生双重态自旋耦合(JPH=cca 20 Cps)，表明质子完全转移，a−…HB+。得出的结论是，结构的急剧变化是由ΔpKa测量的相互作用能逐渐变化引起的。测定了若干共轭配合物[BHB] a−的光谱。当B=B时，形成具有中心对称氢键的同共轭阳离子，JPH随之大幅下降。

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Advances in Molecular Relaxation and Interaction Processes

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