Abstract

Composition, structure, energy parameters, and areas of existence of hydrate complexes formed in the NaClO₄–H₂O system are determined by IR spectroscopy and by quantum chemical methods. It is established that the salt dissociate completely up to the 1:11 molar ratio of components, and the solution contains \(\text{ClO}_4^{-}\) and Na⁺ ions coordinated by four and six water molecules, respectively. In more concentrated solutions (1:11–1:6), NaClO₄·(H₂O)₆ complexes with a completely filled first hydration shell begin to form. The Na⁺ ion in these complexes is coordinated by two oxygen atoms of the \(\text{ClO}_4^{-}\) anion and by four oxygen atoms of water molecules. Solutions with a composition from 1:8.5 to 1:6 contain only partially hydrated NaClO₄·(H₂O)₆ complexes. A further increase of salt concentration (from 1:6 to 1:3.4) leads to the successive formation of NaClO₄·(H₂O)₅, NaClO₄·(H₂O)₄, and NaClO₄·(H₂O)₃ complexes. The changes in the IR spectra of NaClO₄–H₂O solutions in the regions of fundamental and overtone vibrations of water molecules are quantitatively explained using computational data obtained for the composition and structure of NaClO₄·(H₂O)_n (n = 1–7) hydrates. It is established that \(\text{ClO}_4^{-}\) anions exhibit nucleophilic assistance in acid-catalyzed hydrolysis reactions only when they are part of the composition of NaClO₄·(H₂O)_n (n = 3–6) complexes.

中文翻译：

---

NaClO4·(H2O)n (n = 1–7) 水合物的结构和 NaClO4–H2O 体系的平衡组成

摘要

通过红外光谱和量子化学方法测定了NaClO ₄ –H ₂ O 体系中形成的水​​合物复合物的组成、结构、能量参数和存在面积。确定盐完全解离直至组分摩尔比为 1:11，并且溶液包含分别由四个和六个水分子配位的\(\text{ClO}_4^{-}\)和 Na ⁺离子。在更浓的溶液（1:11–1:6）中，开始形成具有完全填充的第一水合壳的NaClO ₄ ·(H ₂ O) _{6络合物。}这些配合物中的Na ⁺离子由\(\text{ClO}_4^{-}\)的两个氧原子配位阴离子和由四个氧原子组成的水分子。组成为1:8.5至1:6的溶液仅含有部分水合的NaClO ₄ ·(H ₂ O) ₆络合物。盐浓度的进一步增加(从1:6到1:3.4)导致连续形成NaClO ₄ ·(H ₂ O) ₅、NaClO ₄ ·(H ₂ O) ₄和NaClO ₄ ·(H ₂ O) ）_3个复合体。_{NaClO 4} –H ₂红外光谱的变化_{使用 NaClO 4} ·(H ₂ O) _n ( n = 1–7)水合物的组成和结构获得的计算数据定量解释了水分子基本振动和泛音振动区域中的 O 溶液 。已确定，\(\text{ClO}_4^{-}\)阴离子仅在属于 NaClO ₄ ·(H ₂ O) _n ( n  = 3组成部分时，才在酸催化水解反应中表现出亲核辅助作用–6) 复合物。