Novel fluorinated indium phosphate with a double-layers structure: Assembled from racemic chiral building units

Assisted by 4,4′-bipyridine (bipy), a new fluorinated indium phosphate, In4F5(HPO4)2(PO4)2(enH)(enH2), has been hydrothermally prepared employing ethylenediamine (en) as structure directing agent (SDA). Single-crystal X-ray diffraction analysis reveals that the compound crystallizes in the monoclinic system with the space group P21/c (No. 14) having cell parameters a = 10.5896(7) Å, b = 10.4575(5) Å, c = 10.2637 Å, β = 99.339(4)°, V = 1121.54(11) Å3, and Z = 2 with R1 = 0.0404. It possesses an unique double-layer structure, which features a racemic mixture of chiral building units. The two chiral building units, one left-handed and one right-handed, alternate to construct a racemic sheet with 8-rings. Pairs of these sheets are bridged together by oxygen and fluorine atoms to form the double layers. The mono- and diprotonated en molecules are located between the double layers to neutralize the negative charge of the inorganic framework. Further characterization of the compound was performed by X-ray powder diffraction, ICP, and TGA analyses.