Equimolar reactions of Et₂Zn with 3,5-dimethylpyrazole (H-pz^Me2), 3,5-di-iso-propylpyrazole (H-pz^iPr2), 3,5-di-tert-butylpyrazole (H-pz^tBu2) and indazole (H-ind) were investigated in toluene or tetrahydrofuran (as a coordinating solvent). A series of diverse ethylzinc pyrazolates and indazolates were identified using advanced NMR spectroscopy and the single crystal X-ray diffraction techniques. The NMR experiments indicate that dimeric moieties of the general formula [EtZn(pz)]₂ or [Et₂Zn₂(pz)₂(THF)] are favoured in solution. Nevertheless, these types of complexes are kinetically labile and tend to undergo ligand scrambling reactions according to the Schlenk equilibrium. For example, the alkyl substituents in the pz^Me2 and pz^iPr2 ligands do not appear to be a strong determinant of the dimeric moieties and the composition of the isolated complexes by crystallisation from the parent reaction mixture varies between spiro-type tri- and tetranuclear aggregates, [Et₂Zn₃(pz)₄(THF)_x] (x = 0 or 2) and [Et₂Zn₄(pz)₆(THF)₂], respectively. The nonstoichiometric formula of these organozinc derivatives is likely related to both the Schlenk-type equilibria and solubility of the respective moieties. In turn, the high steric demands of the 3,5-di-tert-butylpyrazolate ligand promote the dimeric form in solution and the solid state. Interestingly, the ethylzinc indazolate complex also does not undergo a redistribution reaction and yields a dimer.

中文翻译：

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3,5-取代吡唑的乙基锌衍生物的结构多样性

的Et反应等摩尔₂与3,5-二甲基吡唑（H-PZ锌^ME2），3,5-二-异- propylpyrazole（H-PZ ^IPR2），3,5-二-叔-butylpyrazole（H-PZ^吨BU2）和吲唑（H-ind）在甲苯或四氢呋喃（作为配位溶剂）中进行了研究。使用先进的NMR光谱学和单晶X射线衍射技术，鉴定出一系列不同的乙基吡唑锌和吲唑酸酯。NMR实验表明，通式为[EtZn（pz）] ₂或[Et ₂ Zn ₂（pz）_2的二聚部分（THF）]在溶液中是优选的。然而，这些类型的配合物在动力学上不稳定，并且根据Schlenk平衡趋于经历配体加扰反应。例如，pz ^Me2和pz ^iPr2配体中的烷基取代基似乎不是二聚部分的强决定因素，并且从母体反应混合物中结晶出来的分离复合物的组成在螺型三核和四核聚集体之间变化。 ，[Et ₂ Zn ₃（pz）₄（THF）_x ]（x = 0或2）和[Et ₂ Zn ₄（pz）₆（THF）₂]， 分别。这些有机锌衍生物的非化学计量式可能与相应部分的Schlenk型平衡和溶解度有关。反过来，对3,5-二叔丁基吡唑酸酯配体的高空间需求促进了溶液和固态状态下的二聚体形式。有趣的是，吲哚乙基锌锌配合物也不会发生再分布反应，并产生二聚体。