Abstract

The extension of a series of polyalkylpyrazolyl-substituted 2-imidazoline nitronyl nitroxide radicals L^R1/R2/R3 (R = Me, Et, Pr, Bu) enables the synthesis of a number of coordination polymers based on copper(II) bis(hexafluoroacetylacetonate) Cu(hfac)₂ with L^R1/R2/R3. As compared to breathing crystals (Cu(hfac)₂ complexes with monoalkyl-substituted nitroxides L^R1 with bridging μ₂-O,N coordination), the introduction of the second substituent L^R1/R2 into the pyrazole ring allows the performance of the tritopic function of the paramagnetic ligand (μ₃-O,O,N) and the formation of 1D and 2D polymers with original structures and different combinations of [CuO₆], [CuO₅N], [CuO₄N₂], and [CuO₅] coordination cores. Only molecular complexes are obtained with single 3-substituted nitroxide L^R1/R2/R3–L^Me3. The single crystal X-ray diffraction study of the structures of these compounds shows that as in the case of L^Me3, an increase in the size of one of substituents in L^R1/R2 to Pr or Bu causes an increase in distances between paramagnetic centers in two- and three-spin exchange clusters, and correspondingly, spin transitions are absent.

中文翻译：

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具有自旋标记聚烷基吡唑的 Cu(hfac)2 配合物中结构基序的多样性

摘要

一系列聚烷基吡唑基取代的2-咪唑啉硝基氮氧自由基L ^R1/R2/R3 (R = Me, Et, Pr, Bu)的延伸使得能够合成许多基于双(六氟乙酰丙酮酸铜(II))的配位聚合物) Cu(hfac) ₂与 L ^R1/R2/R3。与呼吸晶体（Cu(hfac) ₂与单烷基取代的硝基氧 L ^R1的配合物，具有桥接 μ ₂ -O,N 配位）相比，在吡唑环中引入第二个取代基 L ^R1/R2可以实现三位结构的性能顺磁配体（μ _{3 -O,O,N）的功能以及具有原始结构和[CuO 6} ]、[CuO ₅ N]、[CuO ₄ N ₂ ]和[的不同组合的一维和二维聚合物的形成CuO ₅ ]配位核。仅用单个 3-取代硝基氧 L ^R1/R2/R3 –L ^Me3获得分子复合物。^{这些化合物结构的单晶 X 射线衍射研究表明，与 L Me3}的情况一样，L ^R1/R2中的一个取代基尺寸增加到Pr 或 Bu 会导致顺磁中心之间的距离增加在二自旋和三自旋交换簇中，相应地，不存在自旋跃迁。