NaV1-xP2S6 (x=0.16):: A new compound with infinite straight (1/∞)[V0.837P2S6]- chains that exfoliate forming gels

The new 1D chalcogenophosphate material NaV0.837(6)P2S6 has been synthesized and its structure determined by X-ray powder diffraction analysis. This compound crystallizes in the monoclinic space group P2(1)/n with a = 6.9677(3) Angstrom, b = 5.9059(2) Angstrom, c = 21.4537(s) Angstrom, and beta = 92.962(2)degrees [Z = 4, V = 881.66(8) Angstrom(3)]. The Rietveld refinement led to R-p/R-wp = 0.0208/0.0271 (for 94 parameters refined). The material is isostructural with 1D-NaCrP2S6 and contains infinite (1/infinity)[V0.837(6)P2S6](_) chains consisting of randomly occupied edge-sharing [VS6] octahedra defining zigzag (1/infinity)[VS4] ribbons that are capped by tetradendate [P2S6] ethane-like groups linked to three successive [VS6] polyhedra. Because of the nonstoichiometry of the phase, the charge balance can be written as Na+(V4+)(0.486)(V3+)(0.351)(P4+)(2)(S2-)(6). NaV0.837(6)P2S6 is soluble in strongly polar organic solvents such as N-methylformamide (NMF). The exfoliation of NaV0.837(6)P2S6 in NMF leads to gels or to colored colloidal solutions with complex fluid behavior that depends strongly on concentration.