首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Influence of Hydrogen Bonds in 1:1 Complexes of Phosphinic Acids with Substituted Pyridines on H-1 and P-31 NMR Chemical Shifts
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Influence of Hydrogen Bonds in 1:1 Complexes of Phosphinic Acids with Substituted Pyridines on H-1 and P-31 NMR Chemical Shifts

机译:膦酸中的氢键对H-1和P-31 NMR化学位移中取代吡啶的1:1络合物的影响

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摘要

Two series of 1:1 complexes with strong OHN hydrogen bonds formed by dimethylphosphinic and phenylphosphinic acids with 10 substituted pyridines were studied experimentally by liquid state NMR spectroscopy at 100 K in solution in a low-freezing polar aprotic solvent mixture CDF3/CDClF2. The hydrogen bond geometries were estimated using previously established correlations linking H-1 NMR chemical shifts of bridging protons with the O center dot center dot center dot H and H center dot center dot center dot N interatomic distances. A new correlation is proposed allowing one to estimate the interatomic distance within the OHN bridge from the displacement of P-31 NMR signal upon complexation. We show that the values of P-31 NMR chemical shifts are affected by an additional CH center dot center dot center dot O hydrogen bond formed between the P=O group of the acid and ortho-CH proton of the substituted pyridines. Breaking of this bond in the case of 2,6-disubstituted bases shifts the P-31 NMR signal by ca. 1.5 ppm to the high field.
机译:通过液态NMR光谱通过液态NMR光谱在低聚极性非质子溶剂混合物CDF3 / CDClF2中通过液态NMR光谱通过液态NMR光谱通过液态NMR光谱通过二甲基次膦酸和苯基次膦酸和具有10个取代吡啶形成的强OHN膦酰基膦酰基的两个系列。使用先前建立的相关性与将桥接质子与O中心点中心点中心点H和H中心点中心点中心点N个体组距离连接H-1 NMR化学位移的相关性估计氢键几何形状。提出了一种新的相关性,允许一个人在络合过程中从P-31 NMR信号的位移估计OHN桥内的内部距离。我们表明,P-31 NMR化学位移的值受到在取代吡啶的酸和Ortho-Ch质子的P = O基团之间形成的附加CH中心点中心点中心点O氢键。在2,6-二取代的碱基的情况下破碎该键将P-31 NMR信号通过CA移位。 1.5 ppm到高场。

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