Synthesis and Structural Characterization of Molecular Dy(III) and Er(III) Tetra-Carbonates

Single crystal structures of lanthanide carbonate and hydroxy-carbonate compounds have been previously reported in the literature, with the majority of these compounds being extended one- to three-dimensional compounds. Very few lanthanide compounds have been isolated that contain molecular moieties, and none have been reported for either erbium or dysprosium. Single crystals of the tetra-carbonate complexes, [C(NH2)3]5[Er(CO3)4]·11H2O (I) and [C(NH2)3]4[Dy(CO3)4(H2O)](H3O)·13H2O (II), were isolated from concentrated guanidinium carbonate solutions and characterized by single crystal X-ray diffraction studies. Compounds I and II are the first reported molecular carbonate structures for Er and Dy to be characterized via single crystal X-ray diffraction studies. Crystallographic data for I: monoclinic, space group P21/n, a = 8.8160(6) Å, b = 21.0121(14) Å, c = 19.6496(14) Å, Z = 4. Data for II: tetragonal, space group P4/n, a = b = 15.3199(11) Å, c = 7.5129(11) Å, Z = 2.

此前已有文献报道镧系元素碳酸盐与羟基碳酸盐化合物的单晶结构，其中绝大多数为一维至三维的拓展型化合物。迄今已分离得到的含分子结构单元的镧系化合物极少，且尚未见铒（erbium）或镝（dysprosium）相关此类化合物的报道。从浓碳酸胍溶液中分离得到两种四碳酸根配合物的单晶：[C(NH₂)₃]₅[Er(CO₃)₄]·11H₂O（标记为化合物I）与[C(NH₂)₃]₄[Dy(CO₃)₄(H₂O)](H₃O)·13H₂O（标记为化合物II），并通过单晶X射线衍射（single crystal X-ray diffraction）对其完成结构表征。化合物I与II是首例通过单晶X射线衍射表征的、含铒与镝的分子型碳酸盐结构。化合物I的晶体学数据如下：单斜晶系，空间群P2₁/n，晶胞参数a = 8.8160(6) Å，b = 21.0121(14) Å，c = 19.6496(14) Å，Z = 4；化合物II的晶体学数据如下：四方晶系，空间群P4/n，晶胞参数a = b = 15.3199(11) Å，c = 7.5129(11) Å，Z = 2。