| Popis: |
The title phase, isostructural with the previously reported Zintl phase KtPbg, was synthesized by direct fusion of a stoichiometric amount of the elements at 800 °C for 24 hours and then annealed at 350 °C for 4 weeks. The compound crystallizes in a monoclinic space group, P2\/m, Z = 4, with a = 9.8969(16), b = 13.408(2), c — 16.250(3) Â, and j8 = 103.009(3). The compound contains two different types of Pb/" deltahedra, a monocapped square antiprism and a distorted tricapped trigonal prism. Both cluster geometries correspond to a nido assignment even though the tricapped trigonal prism is not the classic Wade's rules nido deltahedron expected. The geometries and their relationships are discussed, and reasons given for the unusual electron count of the tricapped trigonal prism. |
