H(3)tren (3+) and H(4)tren (4+) fluoride zirconates or tantalates

Four new [H(3)tren](3+) or [H(4)tren](4+) fluoride zirconates and two new [H(3)tren](3+) fluoride tantalates are evidenced in the (ZrF4 or Ta2O5)-tren-HFaq.-ethanol systems at 190 degrees C: the structurally related phases [H(4)tren]center dot(Zr2F12)center dot H2O and alpha-[H(4)tren](center dot)(Zr2F12) (P2(1)2(1)2(1)). beta-[H(4)tren]center dot(Zr2F12) (P2(1/c)), [H(3)tren](4)center dot(ZrF8)(3)center dot 4H(2)O (123). beta-[H(3)tren](2)center dot(Ta3O2F16)center dot(F) (R32) and its monoclinic distortion alpha-[H(3)rren](2)center dot(Ta3O2F16)center dot(F) (C2/m). alpha and beta-[H(4)tren]center dot(Zr2F12) and [H(4)tren]center dot(Zr2F12)center dot H2O are built up from (Zr2F12) dimers of edge sharing ZrF7 polyhedra while isolated ZrF8 dodecahedra are found in [H(3)tren](4)center dot(ZrF8)(3)center dot 4H(2)O. Linear (Ta3O2F16) trimers build et and beta-[H(3)tren](2)center dot(Ta3O2F16)center dot(F); they consist of two (TaOF6) pentagonal bipyramids that are linked to two opposite oxygen atoms of one central (TaO2F4) octahedron. A disorder affects the equatorial fluorine atoms of the trimers and eventually carbon or nitrogen atoms of [H(3)tren](3+) cations. (C) 2011 Elsevier B.V. All rights reserved

2,4,6-Triamino-1,3,5-triazine-1,3-diium aqua­penta­fluoridoaluminate

The title compound, (C3H8N6)[AlF5(H2O)], was obtained by solvothermal synthesis from the reaction of aluminium hydroxide, 1,3,5-triazine-2,4,6-triamine (melamine), aqueous HF and water at 323 K for 48 h. The structure consists of [AlF5(H2O)]2− octa­hedra and diprotonated melaminium cations. Cohesion is ensured by a three-dimensional network of hydrogen bonds

Fluoroaluminates of purine and DNA bases, adenine, guanine: [Hpur](2)center dot(AlF5), [Hade](3)center dot(AlF6)center dot 6.5H(2)O, [Hguan](3)center dot(Al3F12)

New purinium, adeninium and guaninium fluoroaluminates, [Hpur](2)center dot(AlF5), [Hade](3)center dot(AlF6)center dot 6.5H(2)O and [Hguan](3)center dot(Al3F12), are synthesized by microwave heating assisted hydrothermal synthesis at 120 degrees C or 190 degrees C. The crystallisation is difficult; all crystals of [Hpur](2)center dot(AlF6) and [Hade](3)center dot(AlF6)center dot 6.5H(2)O are very small while only a microcrystalline powder of [Hguan](3)center dot(Al3F12) is obtained. The structures are determined from crystal ([Hpur](2)center dot(AlF5) and [Hade](3)center dot(AlF6)center dot 6.5H(2)O) or powder ([Hguan](3)center dot Al3F12)) X-ray diffraction data. In [Hpur](2)center dot(AlF5), trans-chains of corner sharing octahedra lie along the c axis of the tetragonal cell (a = 18.997 (2) angstrom, c = 3.6980(4) angstrom, P4/n, Z = 4). In [Hade](3)center dot(AlF6)center dot 6.5H(2)O, the octahedral AlF6 units lie in (010) planes with water molecules. In [Hguan](3) (Al3F12), trimers of corner sharing octahedra are associated by opposite vertices along the c axis of the trigonal cell (a = 14.254(1) angstrom. c = 3.629(1) angstrom, P3, Z = 1). The purine, adenine and guanine amines are monoprotonated and lie between the preceding chains or layers. Hydrogen bonds between fluoride ions and amine groups of organic cations or, eventually, water molecules ensure the stability of the structures, together with N-H center dot center dot center dot O intermolecular bonds between guaninium cations in [Hguan](3)center dot(Al3F12). The N(7)H-amino and N(9)H-amino tautomeric forms of [Hade](+) are simultaneously found in [Hade](3)center dot(AlF6)center dot 6.5H(2)O. (C) 2010 Elsevier Masson SAS. All rights reserved.</p