Colaneri Michael J, Teat Simon J, Vitali Jacqueline
Department of Chemistry and Physics, State University of New York at Old Westbury, Old Westbury, New York 11568, United States.
Lawrence Berkeley National Laboratory, 1 Cyclotron Road MS 15RO317, Berkeley, California 94720, United States.
J Phys Chem A. 2020 Mar 19;124(11):2242-2252. doi: 10.1021/acs.jpca.0c00004. Epub 2020 Mar 9.
Electron paramagnetic resonance and crystallographic studies on copper-doped cadmium creatininium sulfate (CdCrnS) were undertaken to study the characteristics of a copper-hexahydrate complex in an organic analogue of Tutton's salt. X-ray diffraction experiments determined the crystal structure of CdCrnS at both 100 and 298 K. CdCrnS, like Tutton salt, crystallizes in the monoclinic space group 2/. The unit cell contains two cadmium hexahydrate complexes, four creatininium ions, four sulfates, and four additional solvation waters. Both crystallography and EPR find that the doped copper replaces the cadmium in the structure. Single-crystal EPR measurements at room temperature determined the and copper hyperfine () tensors (principal values: = 2.437, 2.134, and 2.080 and = -327, -84.8, and 7.33 MHz). EPR spectra of the powder at room temperature gave = 2.448, 2.125, and 2.085 and = -315, -75.0, and 35.0 MHz and at 110 K gave = 2.462, 2.116, and 2.077 and = -340, -30.0, and 35.0 MHz. The room-temperature tensors are close to the "rigid lattice limit" values found in copper-doped Tutton salts but with a higher and weaker coupling than average. A small but measurable temperature dependency of the tensors indicated the presence of a dynamic Jahn-Teller (JT) effect. In addition, the EPR line width changed dramatically with temperature, which is like that found in all copper-doped Tutton crystals. Utilizing the model of Silver-Getz for the -value variation gave an estimate for the energy difference (δ = 640 cm) between the ground and next highest JT configurations. An empirical correlation appears to exist between δ and and for the copper hexahydrates studied in similar crystals. This suggests a relationship between the amount of unpaired spins in the copper d-orbital lobe and the gap between wells of the adiabatic potential surface.
对掺杂铜的硫酸镉肌酸酐（CdCrnS）进行了电子顺磁共振和晶体学研究，以探究在图顿盐的有机类似物中六水合铜配合物的特性。X射线衍射实验确定了CdCrnS在100 K和298 K时的晶体结构。CdCrnS与图顿盐一样，结晶于单斜空间群2/ 。晶胞包含两个六水合镉配合物、四个肌酸酐离子、四个硫酸根离子以及四个额外的溶剂化水分子。晶体学和电子顺磁共振研究均发现，掺杂的铜取代了结构中的镉。室温下单晶电子顺磁共振测量确定了 以及铜的超精细（ ）张量（主值： = 2.437、2.134和2.080以及 = -327、-84.8和7.33 MHz）。室温下粉末的电子顺磁共振谱给出 = 2.448、2.125和2.085以及 = -315、-75.0和35.0 MHz，在110 K时给出 = 2.462、2.116和2.077以及 = -340、-30.0和35.0 MHz。室温张量接近在掺杂铜的图顿盐中发现的“刚性晶格极限”值，但 耦合比平均值更高且 耦合比平均值更低。张量存在小但可测量的温度依赖性，表明存在动态 Jahn - Teller（JT）效应。此外，电子顺磁共振线宽随温度显著变化，这与在所有掺杂铜的图顿晶体中发现的情况类似。利用Silver - Getz模型对 值变化进行分析，得到基态与次高JT构型之间能量差（δ = 640 cm）的估计值。对于在类似晶体中研究的六水合铜，δ与 和 之间似乎存在经验相关性。这表明铜d轨道 叶中未成对自旋的数量与绝热势面阱之间的间隙存在关联。
