Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States.
Inorg Chem. 2013 Feb 18;52(4):2199-207. doi: 10.1021/ic3026733. Epub 2013 Feb 1.
A series of new mixed-metal oxalates containing U(4+) and divalent transition metal cations, Na(2)U(2)M(C(2)O(4))(6)(H(2)O)(4) (M = Mn(2+), Fe(2+), Co(2+), and Zn(2+)), were synthesized via a hydrothermal route and structurally characterized by single crystal X-ray diffraction. All of the materials are triclinic, with space group P1. The three-dimensional structure of these isostructural uranates consists of oxalate bridged UO(10) and MO(6) polyhedra. The U(4+) cation is surrounded by five oxalate ligands, while the M(2+) cations are bonded to two oxalate ligands and four water molecules. The magnetic susceptibility data of these mixed metal oxalates were measured as a function of temperature and result in a value of the effective magnetic moment of 3.50 μ(B) for U(4+) cation in the Zn member, while the total effective moment of the Mn(2+), Fe(2+), and Co(2+) members are 6.01, 5.46, and 5.06 μ(B), respectively. For all materials, negative Weiss constants were observed revealing that the materials exhibited local antiferromagnetic interactions. The U(4+) cation exhibits a singlet ground state at low temperature. The materials were further characterized by infrared, UV-vis reflectance spectroscopy, and thermal analysis.
一系列含有 U(4+)和二价过渡金属阳离子的新型混合金属草酸盐，Na(2)U(2)M(C(2)O(4))(6)(H(2)O)(4) (M = Mn(2+)、Fe(2+)、Co(2+)和 Zn(2+)），是通过水热法合成的，并通过单晶 X 射线衍射进行了结构表征。所有的材料都是三斜晶系，空间群为 P1。这些结构同型的铀酸盐的三维结构由草酸盐桥联的 UO(10)和 MO(6)多面体组成。U(4+)阳离子被五个草酸盐配体包围，而 M(2+)阳离子与两个草酸盐配体和四个水分子结合。这些混合金属草酸盐的磁化率数据作为温度的函数进行了测量，结果表明 Zn 成员中 U(4+)阳离子的有效磁矩为 3.50 μ(B)，而 Mn(2+)、Fe(2+)和 Co(2+)成员的总有效磁矩分别为 6.01、5.46 和 5.06 μ(B)。对于所有的材料，都观察到了负 Weiss 常数，这表明这些材料表现出局部反铁磁相互作用。U(4+)阳离子在低温下表现出单重态基态。这些材料还通过红外、紫外-可见反射光谱和热分析进行了进一步的表征。
