The ethane-like [Ge2S6] metals in Na8Pb2[Ge2S6]2, Na8Sn2[Ge2S6]2, and Na8Pb2[Si2Se6]2

Synthesis and characterization of a family of two related quaternary selenides: Na8Eu2(Si2Se6)2 and Na9Sm(Ge2Se6)2

“…Na 8 Eu 2 (Si 2 Se 6 ) 2 I, is isostructural to the previously reported Na 8 Pb 2 (Si 2 Se 6 ) 2 , Na 8 Pb 2 (Ge 2 S 6 ) 2 and Na 8 Sn 2 (Ge 2 S 6 ) 2 [5]. Although this structure-type is not new, to our knowledge, I is the first structure containing both the [Si 2 Se 6 ] 6− unit and a rare earth element.…”

“…These structures both contain ethane-like main group selenide M 2 Se 6 6− (M = Si, Ge) units interconnected with lanthanide cations. Na 8 Eu 2 (Si 2 Se 6 ) 2 is nearly isostructural with Na 8 Pb 2 (Si 2 Se 6 ) 2 [5]. Na 9 Sm(Ge 2 Se 6 ) 2 is a new structure, but it is closely related to Na 8 Eu 2 (Si 2 Se 6 ) 2 .…”

“…When this position was assigned as 100% sodium, the atomic displacement parameter was almost zero. Similar to the treatment of the structure solution for Na 8 Pb 2 (Si 2 Se 6 ) [5], the Eu(1) was partially occupied with Na(1), such that the sum of occupancies was set equal to full occupancy. After least-squares refinement, the relative occupancies refined to 49.8% Eu(1) and 50.2% Na(1), and the isotropic displacement parameter of the Eu(1)/Na(1) site dropped to 0.016Å.…”

“…Unit stoichiometries and predictions based on charge balance can be used to determine reactant stoichiometries that may generate stable structures. Examples of quaternary structures containing main group chalcogenide units include KLaGeSe 4 [4], Na 8 Pb 2 (Si 2 Se 6 ) 2 [5] and a family of potassium lanthanum selenophosphates [6].…”

Flux Synthesis and Isostructural Relationship of Cubic Na1.5Pb0.75PSe4, Na0.5Pb1.75GeS4, and Li0.5Pb1.75GeS4

“…These #uxes are more challenging because as the size of the alkali metal decreases, the basicity decreases along with the probability that the alkali metal will be incorporated into the "nal product (2). Yet, this proved successful in synthesizing Na Pb [Ge S ] (26) and recently Na Pb PSe , Na Pb GeS , and Li Pb GeS , which are isostructural and reported here. Na Pb PSe , Na Pb GeS , and Li Pb GeS could not be made in pure form via direct combination reactions of the elements or the binary chalcogenides; they are products which seem to be stabilized only in the #ux.…”