Hydrothermal synthesis and characterization of a new 3D vanadium(III) phosphite (C 4H 8N 2H 4) 0.5(C 4H 8N 2H 3)[V 4(HPO 3) 7(H 2O) 3]1.5H 2O

Abstract

A new vanadium(III) phosphite, (C 4H 8N 2H 4) 0.5(C 4H 8N 2H 3)[V 4(HPO 3) 7(H 2O) 3]1.5H 2O, has been synthesized hydrothermally by using V 2O 5, H 3PO 3 as reactants, piperazine as the structure-directing agent. The as-synthesized product was characterized by powder X-ray diffraction, IR spectroscopy, inductively coupled plasma analysis, thermogravimetric analysis, and SQUID magnetometer. Single-crystal X-ray diffraction analysis shows that the title compound crystallized in the trigonal space group P 3 ¯ c 1 (No. 165) with the parameters: a = 13.4678 ( 4 ) Å , c = 18.3171 ( 8 ) Å , V = 2877.27 ( 17 ) Å 3 and Z = 4 . Its structure is built up by alternation of octahedral VO 6 or VO 5(H 2O) and pseudo-pyramidal HPO 3 units to form infinite 2D layers, and these layers are interconnected by sharing vertex-oxygen with octahedral VO 6 units to generate a 3D open-framework structure with 12-membered ring channels in a and b directions, respectively, where there exist entrapped diprotonated and mono-protonated piperazine cations, and water molecules. Magnetic measurement indicates that paramagnetic behavior is observed down to 4 K.