H 3tren] 3+ and [H 4tren] 4+ fluoride zirconates or tantalates

Abstract

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 (ZrF 4 or Ta 2O 5)- tren-HF aq.-ethanol systems at 190 °C: the structurally related phases [H 4 tren]·(Zr 2F 12)·H 2O and α-[H 4 tren]·(Zr 2F 12) ( P2 12 12 1), β-[H 4 tren]·(Zr 2F 12) ( P2 1/ c), [H 3 tren] 4·(ZrF 8) 3·4H 2O ( I23), β-[H 3 tren] 2·(Ta 3O 2F 16)·(F) ( R32) and its monoclinic distortion α-[H 3 tren] 2·(Ta 3O 2F 16)·(F) ( C2/ m). α and β-[H 4 tren]·(Zr 2F 12) and [H 4 tren]·(Zr 2F 12)·H 2O are built up from (Zr 2F 12) dimers of edge sharing ZrF 7 polyhedra while isolated ZrF 8 dodecahedra are found in [H 3 tren] 4·(ZrF 8) 3·4H 2O. Linear (Ta 3O 2F 16) trimers build α and β-[H 3 tren] 2·(Ta 3O 2F 16)·(F); they consist of two (TaOF 6) pentagonal bipyramids that are linked to two opposite oxygen atoms of one central (TaO 2F 4) octahedron. A disorder affects the equatorial fluorine atoms of the trimers and eventually carbon or nitrogen atoms of [H 3 tren] 3+ cations.