Department of Civil and Environmental Engineering and Earth Sciences , University of Notre Dame , Notre Dame , Indiana 46556 , United States.
Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute , University of Minnesota , Minneapolis , Minnesota 55455 , United States.
Inorg Chem. 2019 Sep 16;58(18):12264-12271. doi: 10.1021/acs.inorgchem.9b01712. Epub 2019 Aug 26.
Little is known about the crystal chemistry of neptunyl peroxide compounds compared to uranyl peroxide compounds, for which dozens of structures have been described. Uranyl peroxides are formed over a broad range of pH and solution conditions, but neptunyl peroxide chemistry is complicated by the ability of HO to act as an oxidizing or reducing agent for Np, depending on the conditions present. The combination of Np(V) in 1 M HCl, HO, and CaCl under alkaline conditions leads to the immediate crystallization of a neptunyl triperoxide monomer, Ca[NpO(O)]·9HO, which is the first Np(VI)-based peroxide compound to be characterized in the solid state and is isostructural to Ca[UO(O)]·9HO. The crystal structure reveals bond distances of 1.842(7) Å that are the longest reported to date for nonbridging Np(VI)-O bonds. Computational studies probe the oxidation state and bond distances of the monomer unit and differences in Raman spectra of the neptunyl and uranyl triperoxide compounds.
与已描述数十种结构的铀（VI）过氧化物化合物相比，人们对六价锝过氧化物化合物的晶体化学了解甚少。铀（VI）过氧化物在较宽的 pH 值和溶液条件范围内形成，但由于 HO 可根据存在的条件充当 Np 的氧化剂或还原剂，因此六价锝过氧化物化学变得复杂。在碱性条件下，1 M HCl、HO 和 CaCl 中的 Np(V)结合，立即结晶出一种六价锝三过氧化物单体 Ca[NpO(O)]·9HO，这是第一个在固态下被表征的基于 Np(VI)的过氧化物化合物，并且与 Ca[UO(O)]·9HO 同构。晶体结构揭示了 1.842(7)Å 的键长，这是迄今为止报道的最长的非桥接 Np(VI)-O 键。计算研究探测了单体单元的氧化态和键长以及三过氧铀（VI）和三过氧锝（VI）化合物的拉曼光谱的差异。
