Framework Solids Laboratory, Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore-560 012, India.
Inorg Chem. 2010 Mar 15;49(6):2931-47. doi: 10.1021/ic902472h.
Hydrothermal reactions between uranium salts and arsenic pentoxide in the presence of two different amines yielded six new uranium arsenate phases exhibiting open-framework structures, ethylenediamine (en): [C(2)N(2)H(9)][(UO(2))(AsO(4))], I; [C(2)N(2)H(10)](UO(2))F(HAsO(4)) x 4 H(2)O, II; [C(2)N(2)H(9)][U(2)F(5)(HAsO(4))(2)], III; [C(2)N(2)H(9)][UF(2)(AsO(4))], IV; diethylenetriamine (DETA), [C(4)N(3)H(16)][U(2)F(3)(AsO(4))(2)(HAsO(4))], V; and [C(4)N(3)H(16)][U(2)F(6)(AsO(4))(HAsO(4))], VI. The structures were determined using single crystal studies, which revealed two- (I, II, V) and three-dimensional (III, IV, VI) structures for the uranium arsenates. The uranium atom, in these compounds, exhibits considerable variations in the coordination (6 to 9) that appears to have some correlation with the synthetic conditions. The water molecules in [C(2)N(2)H(10)](UO(2))F(HAsO(4)) x 4 H(2)O, II, could be reversibly removed, and the dehydrated phase, [C(2)N(2)H(10)](UO(2))F(HAsO(4)), IIa, was also characterized using single crystal studies. The observation of many mineralogical structures in the present compounds suggests that the hydrothermal method could successfully replicate the geothermal conditions. As part of this study, we have observed autunite, Ca(UO(2))(PO(4))(H(2)O)(11), metavauxite, [Fe(H(2)O)(6)]Al(OH)(H(2)O)(PO(4)), linarite, PbCu(SO(4))(OH)(2), and tancoite, LiNa(2)H[Al(PO(4))(2)(OH)], structures. The repeated observation of the secondary building unit, SBU-4, in many of the uranium arsenate structures suggests that these are viable building units. Optical studies on the uranium arsenate compound, [C(4)N(3)H(16)][U(2)F(6)(AsO(4))(HAsO(4))], VI, containing uranium in the +4 oxidation state indicates a blue emission through an upconversion process. The compound also exhibits antiferromagnetic behavior.
水热反应在两种不同的胺存在下，铀盐和五氧化二砷之间生成了六个具有开放骨架结构的新型铀砷酸盐相，乙二胺（en）：[C(2)N(2)H(9)][(UO(2))(AsO(4))]，I；[C(2)N(2)H(10)](UO(2))F(HAsO(4))x4H(2)O，II；[C(2)N(2)H(9)][U(2)F(5)(HAsO(4))(2)]，III；[C(2)N(2)H(9)][UF(2)(AsO(4))]，IV；二乙烯三胺（DETA）：[C(4)N(3)H(16)][U(2)F(3)(AsO(4))(2)(HAsO(4))]，V；和[C(4)N(3)H(16)][U(2)F(6)(AsO(4))(HAsO(4))]，VI。这些结构通过单晶研究确定，揭示了铀砷酸盐的二维（I、II、V）和三维（III、IV、VI）结构。在这些化合物中，铀原子的配位变化很大（6 到 9），这似乎与合成条件有关。在[C(2)N(2)H(10)](UO(2))F(HAsO(4))x4H(2)O，II 中的水分子可以可逆地去除，脱水相[C(2)N(2)H(10)](UO(2))F(HAsO(4))，IIa，也通过单晶研究进行了表征。本研究中观察到许多矿物结构，表明水热法可以成功复制地热条件。作为本研究的一部分，我们观察到了钙铀磷矿，Ca(UO(2))(PO(4))(H(2)O)(11)、水羟铝铁石，[Fe(H(2)O)(6)]Al(OH)(H(2)O)(PO(4))、蓝铜矿，PbCu(SO(4))(OH)(2)和钠锂砷磷石，LiNa(2)H[Al(PO(4))(2)(OH)]的结构。在许多铀砷酸盐结构中观察到重复的二级构建单元 SBU-4，表明这些是可行的构建单元。对含有+4 氧化态铀的铀砷酸盐化合物[C(4)N(3)H(16)][U(2)F(6)(AsO(4))(HAsO(4))]的光学研究表明，通过上转换过程，它发出蓝色发射。该化合物还表现出反铁磁行为。
