Polychalcogenophosphate flux synthesis of 1D-KInP2Se6 and 1D and 3D-NaCrP2S6

Abstract

Three new chalcogenophosphates, 1D-KInP2Se6 (I), 1D-NaCrP2S6 (II) and 3D-NaCrP2S6 (III), have been synthesized and their structure determined from single crystal diffraction analysis. (I) and (II) crystallize in the monoclinic system (space group P21/n, No. 14) with cell parameters a=7.5112(11), b=6.4861(5), c=22.789(2) Å and β=98.912(16)° (V=1096.9(2) Å3), Z=4 and R/Rw(F2)=0.0234/0.0387 (for 900 observed reflections and 92 refined parameters) for (I) and a=7.0279(5), b=5.8797(2), c=21.2578(14) Å and β=92.110(3)° (V=877.82(9) Å3), Z=4 and R/Rw(F2)=0.0572/0.1151 (for 1455 observed reflections and 92 refined parameters) for (II). Both materials exhibit 1/∞[MP2Q6]− chains built upon [MQ6] octahedra (M=In, Cr; Q=Se, S) sharing edges to define 1/∞[MQ4]5− zigzag fibers which are capped by tetradentate ethane-like [P2Q6] groups. (III) crystallizes in the orthorhombic system (space group Fdd2, No. 43) with cell parameters a=10.9742(7), b=7.9828(6), c=20.8590(19) Å (V=1827.3(4) Å3), Z=8 and R/Rw=0.0184/0.0378 (for 967 observed reflections and 47 refined parameters), and displays a three-dimensional framework arrangement. Its structure is similar to that of TiP2S6 where titanium atoms are substituted for the chromium, the sodium atoms being inserted in the empty tunnels to ensure the charge balance. The exfoliation properties of 1D-NaCrP2S6 in polar solvents are reported.