29Si NMR spectroscopy, the method of continuous variations, and density functional theory computations show that sodium hexamethyldisilazide (NaHMDS) is a disolvated dimer in toluene, a mixture of disolvated dimer and tetrasolvated monomer in THF/toluene, and exclusively monomer in neat THF. The dioxane-solvated NaHMDS only partially deaggregates to monomer even in neat dioxane. 15N-29Si coupling constants and 29Si chemical shifts show a high and dependable correlation with the aggregation state. Monitoring either chemical shift or coupling constant versus THF concentration even in the high-temperature, rapid-exchange limit affords the solvation numbers consistent with DFT computations. The preparation of 15N-labeled NaHMDS has been improved.

中文翻译：

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六甲基二硅叠氮化钠：使用 15N–29Si 标量耦合确定聚集和溶剂化状态

29Si NMR 光谱、连续变化方法和密度泛函理论计算表明，六甲基二硅叠氮化钠 (NaHMDS) 是甲苯中的二聚体、四溶剂化二聚体和四溶剂化单体在 THF/甲苯中的混合物，以及纯 THF 中的唯一单体。即使在纯二恶烷中，二恶烷溶剂化的 NaHMDS 也仅部分解聚为单体。15N-29Si 耦合常数和 29Si 化学位移显示出与聚集状态高度可靠的相关性。即使在高温、快速交换极限下监测化学位移或偶联常数与 THF 浓度的关系，也能提供与 DFT 计算一致的溶剂化数。15N 标记的 NaHMDS 的制备得到了改进。