An Inorganic Double Helix Sheathing Alkali Metal Cations: ANb₂P₂S₁₂ (A=K, Rb, Cs), A Series of Thiophosphates Close to the Metal–Nonmetal Boundary—Chalcogenide Analogues of Transition‐Metal Phosphate Bronzes?

Abstract

The new quaternary niobium thiophosphates ANb(2)P(2)S(12) (A=K, Rb, Cs) have been prepared and characterized. The title compounds were synthesized by reacting Nb metal, A(2)S, P(2)S(5), and S at 600-700 degrees C in evacuated silica tubes. They crystallize as "stuffed" variants of the tetragonal TaPS(6) structure type in the tetragonal space group I$\bar 4$2d with eight formula units per unit cell and lattice constants a=15.923(2) and c=13.238(3) A for CsNb(2)P(2)S(12), a=15.887(3) and c=13.132(3) A for RbNb(2)P(2)S(12), and a=15.850(2) and c=13.119(3) A for KNb(2)P(2)S(12). Their structures are based on double helices formed from interpenetrating, noninteracting spiral chains of binuclear [Nb(2)S(12)] cluster units and [PS(4)] thiophosphate groups. The cavities and tunnels, which are formed by the helical chains, are filled with A(+) ions. Temperature-dependent conductivity studies reveal thermally activated electrical transport behavior. This result is consistent with the observation of a temperature-dependent contribution to the (31)P MAS-NMR shift, suggesting that the delocalized s-electron spin density increases with increasing temperature. These findings are supported by the results of tight-binding band structure calculations which reveal that the unusual electrical transport behavior of ANb(2)P(2)S(12) is a consequence of the structure symmetry. Therefore, CsNb(2)P(2)S(12) may be considered a chalcogenide analogue of metal phosphate bronzes.

Monitoring Binding of HIV‐1 Capsid Assembly Inhibitors Using 19F Ligand‐and 15N Protein‐Based NMR and X‐ray Crystallography: Early Hit Validation of a Benzodiazepine Series

“…Remarkably, except for a few examples such as TaPS 6 ,25b A Ti 2 (PS 4 ) 3 ( A = Li, Na, Ag), [25c, 40] A Nb 2 P 2 S 12 ( A = K, Rb, Cs),41 or Ag 2 NbTi 2 P 6 S 25 40 open framework chalcogenide structures are obtained typically only with soft (according to Pearson) metals. However, high and variable coordination numbers of the early transition metals, [19, 30, 31] lanthanides, [26, 42] or actinides [16, 30, 43] combined with the condensation equilibria of chalcophosphates44 may lead to structural arrangements of astounding complexity, as the above examples indicate.…”

Cs3UP2S8, a Coordination Polymer Containing the Unprecedented [U=S]2+ Sulfidouranium(2+) Moiety

“…The structures of the title compound Cs 3 UP 2 S 8 and the uranium thiophosphates U(P 2 S 6 ) 2 ,28 CsLiU(PS 4 ) 2 ,29 and other framework compounds like TaPS 6 ,41 A Ti 2 (PS 4 ) 3 ( A = Li, Na, Ag),42 A Nb 2 P 2 S 12 ( A = K, Rb, Cs),43 Ag 2 NbTi 2 P 6 S 25 ,44 A 11 U 7 (PS 4 ) 13 ( A = K, Rb),45 or Ln 4 (GeS 4 ) 3 ( Ln = Ce, Nd)46–48 indicate that many uranium – and in an analogoues fashion early transition metal – thiophosphates might conceptually be assembled by a simple LEGO‐type approach according to the following recipe: (i) the uranium atoms act as pseudotetrahedral centers of connectivity, (ii) the bi‐ or tridentate thiophosphate ligand groups take the role of rod‐like connectors, (iii) the general assemblage of corner sharing U(thiophosphate) 4 pseudotetrahedra follows the rules established for silicate networks. (iv) The structure of Cs 3 UP 2 S 8 presents an extension to these simple guidelines as the terminal =S moiety may substitute for a thiophosphate group but – as a terminal ligand – represents a dead end in the above connectivity pattern.…”

Comprehensive Uranium Thiophosphate Chemistry: Framework Compounds Based on Pseudotetrahedrally Coordinated Central Metal Atoms

“…Network formation requires the presence of high symmetry branching units such as Ti(PS 4 ) 3 (3-fold) [58] or and Nb 2 (S 2 ) 2 (PS 4 ) 4 (4-fold) [69] combined with connecting elements having linear, tetrahedral, or square-planar coordinating abilities (e.g. PS 4 3-, P 2 S 6 2-/P 2 S 6 4-, or P 2 S 8 4-groups).…”

“…PS 4 3-, P 2 S 6 2-/P 2 S 6 4-, or P 2 S 8 4-groups). Typical examples are the title compounds, NaTi 2 (PS 4 ) 3 , [58] Ag 2 NbTi 3 P 6 S 25 , [57] ANb 2 P 2 S 12 , [69] CsMP 2 S 8 ϵCs 2 M 2 (PS 4 ) 2 (P 2 S 8 ) (M = Sn, Ti), [70] and CsTa 4 P 3 S 19 .…”