Krizan Jason W, Pulido Sergio H, Wehrhan Sarah E, Chan Benny C
Department of Chemistry, College of New Jersey, 2000 Pennington Rd, Ewing, NJ 08628, USA.
Acta Crystallogr C. 2010 Jul;66(Pt 7):i75-8. doi: 10.1107/S0108270110017038. Epub 2010 Jun 17.
The title compounds, namely hexacaesium tetraniobium docosaselenide and dodecapotassium hexaniobium pentatriacontaselenide, were formed from their respective alkali chalcogenide reactive flux and niobium metal. Both compounds fall into the larger family of solid-state compounds that contain the M(2)Q(11) building block (M = Nb, Ta; Q = Se, S), where the metal chalcogenide forms dimers of face-shared pentagonal bipyramids. Cs(6)Nb(4)Se(22) contains two Nb(2)Se(11) building blocks linked by an Se-Se bond to form isolated Nb(4)Se(22) tetrameric building blocks surrounded by caesium ions. K(12)Nb(6)Se(35.3) contains similar Nb(4)Se(22) tetramers that are linked by an Se-Se-Se unit to an Nb(2)Se(11) dimer to form one-dimensional anionic chains surrounded by potassium ions. Further crystallographic studies of K(12)Nb(6)Se(35.3) demonstrate a new M(2)Se(12) building block because of disorder between an Se(2-) site (85%) and an (Se-Se)(2-) unit (15%). The subtle differences between the structures are discussed.
标题化合物，即六铯四铌二十二硒化物和十二钾六铌三十五硒化物，由它们各自的碱金属硫族化物反应性助熔剂和铌金属形成。这两种化合物都属于包含M(2)Q(11)结构单元（M = Nb，Ta；Q = Se，S）的固态化合物大家族，其中金属硫族化物形成面共享五角双锥的二聚体。Cs(6)Nb(4)Se(22)包含两个通过Se - Se键连接的Nb(2)Se(11)结构单元，形成被铯离子包围的孤立Nb(4)Se(22)四聚体结构单元。K(12)Nb(6)Se(35.3)包含类似的Nb(4)Se(22)四聚体，它们通过一个Se - Se - Se单元与一个Nb(2)Se(11)二聚体相连，形成被钾离子包围的一维阴离子链。对K(12)Nb(6)Se(35.3)的进一步晶体学研究表明，由于一个Se(2-)位点（85%）和一个(Se - Se)(2-)单元（15%）之间的无序，出现了一种新的M(2)Se(12)结构单元。讨论了这些结构之间的细微差异。
