Proton spin relaxation and exchange properties of hydrated chromic ions in H2O and H2O-D2O mixtures
Proton spin relaxation and exchange properties of hydrated chromic ions in H2O and H2O-D2O mixtures
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H2O和H2O-D2O混合物中水合铬离子的质子自旋弛豫和交换特性
DOI：
10.1021/j100845a019
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发表时间：
1969
期刊：
影响因子：
--
通讯作者：
V. Pollak
中科院分区：
文献类型：
--
作者：
B. Melton;V. Pollak
实验结果表明，在1.1 G ~ 14 kG的电场和0 ~ 99℃的温度范围内，H20和h2o的混合物在Cr （III）溶液中的质子自旋弛豫。含有0.10 M HClOi的水溶液给出的结果仅反映了Cr (H20) 63+的弛豫和交换性质，而不受水解产物或聚合物的影响，这些产物或聚合物会引起热滞后，也不受酸催化的质子交换的影响，这种影响存在于高酸度的溶液中。对弱酸化溶液的测量证实，Cr (H20) e3+是比Cr (H20) 60H2+更强的弛豫物质，但后者与溶剂水的质子交换更快。提出了一种涉及配位OH离子的均相（局部）质子交换机制来解释这一结果。对含有不同摩尔分数H-的0.10 Mhcio4溶液的测量。0和DsO表明，低温下氘化的主要作用是增加Cr3+初级水化球中质子的寿命，这是由于H20的碱度比D20大。在高温下，2保持不变，而由于水合络合物的旋转运动减慢，2随着氘化而减少。后者与从H20到D20的粘度显著增加有关。
Experimental results are presented on proton spin relaxation in Cr (III) solutions of H20 and mixtures of H20 and DaO, in fields from 1.1 G to 14 kG, and at temperatures from 0 to 99. Water solutions containing 0.10 M HClOi give results which reflect the relaxation and exchange properties of Cr (H20) 63+ alone, uncomplicatedby the effects of hydrolysis products or polymers which cause thermal hysteresis or by acid-catalyzed proton ex-change which is present in solutions of high acidity. Measurements on weakly acidified solutions confirm that Cr (H20) e3+ is a more strongly relaxing species than Cr (H20) 60H2+, but the latter undergoes more rapid proton exchange with the solvent water. A homogeneous (local) proton exchange mechanism involving the coordinated OH” ion is proposed to account for this result. Measurements on 0.10 Mhcio4 solutions containing varying mole fractions of H-. 0 and DsO indicate that the principal effect of deuterationat low temperatures is an increase in the lifetime of protons in the primary hydration sphere of Cr3+, resulting from the greater basicity of H20 as compared to D20. At high temperatures 2 remains constant, whereas decreases with deuteration due to slower rotational motion of the hydrated complex. The latter is correlated with the marked increase in viscosity which occurs in going from H20 to D20.