仲铵阳离子和叔铵阳离子在层状亚硒酸铀酰的形成过程中是否充当结构导向剂？

Do secondary and tertiary ammonium cations act as structure-directing agents in the formation of layered uranyl selenites?

作者信息

Almond Philip M, Albrecht-Schmitt Thomas E

机构信息

Department of Chemistry, Auburn University, Auburn, Alabama 36849, USA.

出版信息

Inorg Chem. 2003 Sep 8;42(18):5693-8. doi: 10.1021/ic034308d.

DOI:10.1021/ic034308d

PMID:12950219

Abstract

Two new layered uranyl selenites, C(4)H(12)N(2)[UO(2)(HSeO(3))(SeO(3))] (1) and C(6)H(14)N(2)[UO(2)(HSeO(3))(SeO(3))].0.5H(2)O.0.5CH(3)CO(2)H (2), have been isolated from mild hydrothermal reactions. The preparation of 1 was achieved by reacting UO(2)(C(2)H(3)O(2))(2).2H(2)O with H(2)SeO(4) in the presence of piperazine at 130 degrees C for 2 d. Crystals of 2 were synthesized by reacting UO(2)(C(2)H(3)O(2))(2).2H(2)O, H(2)SeO(4), and 1,4-diazabicyclo[2.2.2]octane at 150 degrees C for 2 d. The structure of 1 consists of UO(2)(2+) cations that are bound by bridging HSeO(3)(-) anions and chelating/bridging SeO(3)(2)(-) anions to yield UO(7) pentagonal bipyramids. The joining of the uranyl moieties by the hydrogen selenite and selenite anions creates two-dimensional 2(infinity) UO(2)(HSeO(3))(SeO(3)) layers that extend in the bc-plane. The stereochemically active lone pair of electrons on the HSeO(3)(-) and SeO(3)(2)(-) anions align along the a-axis making each layer polar. The 2(infinity)UO(2)(HSeO(3))(SeO(3)) layers and piperazinium cations stack in a AA'BAA'B sequence where two layers stack on one another without intervening piperazinium cations. While each 2(infinity)UO(2)(HSeO(3))(SeO(3)) layer is polar, in the AA' stacking, the polarity of the second sheet is reversed with respect to the first, yielding an overall structure that is centrosymmetric. The structure of 2 is constructed from uranyl cations that are bound by three bridging SeO(3)(2)(-) and two bridging HSeO(3)(-) anions to create UO(7) pentagonal bipyramids. The linking of the uranyl cations by the HSeO(3)(-) and SeO(3)(2-) anions creates 2(infinity)UO(2)(HSeO(3))(SeO(3)) layers that extend in the ac-plane. In 1 and 2, the organic ammonium cations form hydrogen bonds with the anionic uranyl selenite layers. Crystallographic data: 1, monoclinic, space group P2(1)/c, a = 10.9378(5) A, b = 8.6903(4) A, c = 9.9913(5) A, beta = 90.3040(8) degrees, Z = 4; 2, orthorhombic, space group Pnma, a = 13.0858(8) A, b = 17.555(1) A, c = 10.5984(7) A, Z = 8.

摘要

通过温和水热反应分离出了两种新型层状亚硒酸铀酰化合物，[C₄H₁₂N₂]₀.₅[UO₂(HSeO₃)(SeO₃)] （1）和[C₆H₁₄N₂]₀.₅[UO₂(HSeO₃)(SeO₃)].0.5H₂O.0.5CH₃CO₂H （2）。1的制备是通过在130℃下，使UO₂(C₂H₃O₂)₂·2H₂O与H₂SeO₄在哌嗪存在下反应2天实现的。2的晶体是通过使UO₂(C₂H₃O₂)₂·2H₂O、H₂SeO₄和1,4 - 二氮杂双环[2.2.2]辛烷在150℃下反应2天合成的。1的结构由UO₂²⁺阳离子组成，这些阳离子通过桥连的HSeO₃⁻阴离子和螯合/桥连的SeO₃²⁻阴离子结合，形成UO₇五角双锥体。亚硒酸氢根和亚硒酸根阴离子将铀酰部分连接起来，形成二维的2(∞)[UO₂(HSeO₃)(SeO₃)]⁻层，该层在bc平面上延伸。HSeO₃⁻和SeO₃²⁻阴离子上立体化学活性孤对电子沿a轴排列，使每层都具有极性。2(∞)[UO₂(HSeO₃)(SeO₃)]⁻层和哌嗪鎓阳离子以AA'BAA'B序列堆积，其中两层相互堆叠，中间没有哌嗪鎓阳离子。虽然每个2(∞)[UO₂(HSeO₃)(SeO₃)]⁻层都具有极性，但在AA'堆积中，第二层的极性相对于第一层是相反的，从而产生一个整体中心对称的结构。2的结构由铀酰阳离子构成，这些阳离子通过三个桥连的SeO₃²⁻和两个桥连的HSeO₃⁻阴离子结合，形成UO₇五角双锥体。HSeO₃⁻和SeO₃²⁻阴离子将铀酰阳离子连接起来，形成在ac平面上延伸的2(∞)[UO₂(HSeO₃)(SeO₃)]⁻层。在1和2中，有机铵阳离子与阴离子亚硒酸铀酰层形成氢键。晶体学数据：1，单斜晶系，空间群P2(1)/c，a = 10.9378(5) Å，b = 8.6903(4) Å，c = 9.9913(5) Å，β = 90.3040(8)°，Z = 4；2，正交晶系，空间群Pnma，a = 13.0858(8) Å，b = 17.555(1) Å，c = 10.5984(7) Å，Z = 8。