Abstract A detailed Fourier-transform infrared spectroscopic study of protiated and series of deuterated analogues of chromium(II) saccharinate hexahydrate has been carried out. The spectral appearances in the regions of O–H and O–D stretching modes (particularly those corresponding to the isotopically isolated, i.e. uncoupled oscillators) strongly imply that the hydrogen bonding network in the studied compound is similar to that in the case of copper(II) saccharinate hexahydrate, which is somewhat different from the other members of the isomorphous series of metal(II) saccharinates hexahydrates. Therefore, a reinvestigation of the hydrogen bonding network structure in the title system by neutron diffraction technique is proposed. The similarity of the hydrogen bonding network in the mentioned two compounds is due to the presence of a Jahn–Teller active ion in both of them, which, in a non-ideal octahedral immediate surrounding leads to a second-order (or pseudo-) Jahn–Teller effect. This is clearly seen e.g. from the bond length distortion indices which are an order of magnitude higher in the chromium and copper compounds as compared to the other members of the isomorphous series, that do not contain a Jahn-Teller active ion. A very good correlation between the crystallographically determined proton donor – proton acceptor O···O distances and the experimentally measured O–D stretching frequencies of the corresponding uncoupled oscillators has been found in the studied compound. The derived correlation equation has an excellent predictive value within a rather wide range of distances/frequencies.

中文翻译：

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具有伪 Jahn-Teller 效应的系统中特征氢键模式的光谱证据：六水合糖精二价铬

摘要 对六水合糖精二价铬的质子化和一系列氘化类似物进行了详细的傅里叶变换红外光谱研究。O-H 和 O-D 伸缩模式区域的光谱外观（特别是那些对应于同位素隔离的，即非耦合振荡器）强烈暗示所研究化合物中的氢键网络与铜的情况相似（ II) 糖精六水合物，它与金属(II) 糖精六水合物同晶系列的其他成员有些不同。因此，提出通过中子衍射技术重新研究标题体系中的氢键网络结构。上述两种化合物中氢键网络的相似性是由于它们中都存在 Jahn-Teller 活性离子，在非理想的八面体周围会导致二阶（或伪）雅恩-泰勒效应。这可以从例如键长畸变指数清楚地看出，与不包含Jahn-Teller活性离子的同晶系列的其他成员相比，铬和铜化合物中的键长畸变指数高一个数量级。在所研究的化合物中发现了晶体学确定的质子供体 - 质子受体 O···O 距离与实验测量的相应非耦合振荡器的 O-D 伸缩频率之间非常好的相关性。