Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
Inorg Chem. 2010 Sep 6;49(17):7935-40. doi: 10.1021/ic100940b.
Reported are the synthesis, the structural characterization, and the electronic band structures of two new Zintl phases: BaGa2P2 and BaGa2As2. Both compounds are isoelectronic and isotypic and crystallize in a monoclinic system with a new structure type (Pearson symbol mP20). The structures have been established by single-crystal X-ray diffraction, space group P2(1)/c (Z = 4), with lattice parameters as follows: a = 7.3363(13)/7.495(5) Å; b = 9.6648(17)/9.901(6) Å; c = 7.4261(13)/7.643(5) Å; beta = 115.373(2) degrees/115.381(8) degrees for BaGa2P2/BaGa2As2, respectively. The atomic arrangements in both cases are devoid of disorder and are best rationalized as polyanionic layers, (infinity)(2)[Ga2Pn2]2- (Pn = P, As), with Ba2+ cations separating them. The layers, in turn, can be viewed as the result of condensation of Ga2Pn6 units, which are isosteric with the ethane molecule in its staggered conformation. Structural parallels with other known Zintl phases are presented. The electronic structures, computed using the tight-binding linear muffin-tin orbital methods (TB-LMTO), are discussed as well.
报道了两种新的 Zintl 相：BaGa2P2 和 BaGa2As2 的合成、结构特征和电子能带结构。这两种化合物是等电子和同型的，均结晶为具有新结构类型（Pearson 符号 mP20）的单斜系统。结构通过单晶 X 射线衍射、空间群 P2(1)/c（Z = 4）确定，晶格参数如下：a = 7.3363(13)/7.495(5) Å；b = 9.6648(17)/9.901(6) Å；c = 7.4261(13)/7.643(5) Å；β = 115.373(2)°/115.381(8)°，分别为 BaGa2P2/BaGa2As2。两种情况下的原子排列都没有无序，可以最好地解释为多阴离子层，（无限）（2）[Ga2Pn2]2-（Pn = P，As），其中 Ba2+阳离子将它们隔开。这些层又可以看作是 Ga2Pn6 单元的缩合产物，这些单元与交错构象的乙烷分子在结构上是等体的。还提出了与其他已知 Zintl 相的结构相似之处。使用紧束缚线性 muffin-tin 轨道方法（TB-LMTO）计算的电子结构也进行了讨论。
