Synthesis and characterisation of MIL-43 and MIL-44, two new layered templated tetravalent phosphates: Zr(PO4)(2)center dot N2C2H10 and Ti-2(PO4)(2)(HPO4)(2)center dot N2C2H10

Zr(PO4)(2).N2C2H10 or MIL-43 and Ti-2(PO4)(2)(HPO4)(2).N2C2H10 or MIL-44 we re prepared hydrothermally (20 or 4 days, 473 or 453 K, respectively, autog enous pressure) in the presence of ethylenediamine. Their structures have b een determined by single-crystal X-ray diffraction. MIL-43 crystallises in the monoclinic space group P2(1) (No. 4) with a = 11.0722(1), b = 10.6631() , c = 16.4642(2) Angstrom, beta= 95.991 (1)degrees and V = 1933.21(3) Angst rom (3) (final agreement factors R-1 (F) = 0.0466, wR(2) (F-2) = 0. 1096). Due to the very poor quality of the crystal, only an approached structure o f MIL-44 is given; it crystallises in the triclinic space group P1 (No. 1) with a = 5.0845(4), b = 6.3097(5), c = 12.6111(9) Angstrom, alpha = 17.454( l), beta = 78.926(2), gamma = 89.986(1)degrees and V = 387.21(5) Angstrom ( 3). Both solids are two-dimensional and are the ion-exchanged equivalents o f the layered solids alpha ZrP and gamma TiP. Inorganic sheets of MIL-43 ar e built up from pseudo-hexagonal arrays of ZrO6 Octahedra surrounded by PO4 tetrahedra pointing their terminal oxygen alternatively up and down at the interlayer space. Layers of MIL-44 are made of double -(Ti-O-P)- chains bu ilt from TiO6 Octahedra and PO4 tetrahedra on which HPO4 groups are grafted pointing towards the interlayer space. In both cases, diprotonated organic templates, located between the layers, interact with terminal phosphate gr oups and ensure via hydrogen bonds the stability of the structures. (C) 200 1 Editions scientifiques et medicales Elsevier SAS. All rights reserved.