Synthesis and structural characterization of (H 4APPIP)[V 3(C 2O 4) 2(HPO 4) 3(PO 4)(H 2O)]·6H 2O (APPIP=1,4-bis(3-aminopropyl)piperazine), a layered vanadium oxalatophosphate containing double 6-ring units

Abstract

A new vanadium(III) oxalatophosphate has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction and thermogravimetric analysis. It crystallizes in the triclinic space group P 1 ̄ with a=11.604(2) Å, b=12.391(2) Å, c=15.220(3) Å, α=71.090(3)°, β=82.630(3)°, γ=62.979(3)°, V=1843.8(5) Å 3 and Z=2. The structure consists of V 6(HPO 4) 6 double 6-ring (D6R) units connected by coordinating C 2O 4 2− and PO 4 3− anions to form anionic sheets in the ab plane with charge-compensating quadruply protonated 1,4-bis(3-aminopropyl)piperazinium cations and water molecules between the sheets. It is one of the few compounds with 2D layer structures and the second example containing D6R units in the system of metal oxalatophosphates. The iron analogue was also synthesized.