The cocrystallization of the cubicphases with the coexistence of [Ta6Br12]2+ and [Ta6Br12]4+ in the latter

Author(s): Marija Vojnovic, Nevenka Brnicevic, I Basic, Pavica Planinic, Gerald Giester
Abstract: Cubic [Ta6Br12(H2O)6][CuBr2 X2]ž10H2O and triclinic [Ta6Br12(H2O)6]X2žtrans- [Ta6Br12(OH)4(H2O)2] ž18H2O (X = Cl, Br, NO3) cocrystallize in aqueous solutions of [Ta6Br12]2+ in the presence of Cu2+ ions. The crystal structures of [Ta6Br12(H2O)6]Cl2 žtrans-[Ta6Br12(OH)4(H2O) 2]ž18H2O (1) and [Ta6Br12(H2O)6]Br2 žtrans-[Ta6Br12(OH)4(H2O) 2]ž18H2O (3) have been solved in the triclinic space group P 1¯ (No. 2). Crystal data: 1, a = 9.3264(2) A°, b = 9.8272(2) A°, c = 19.0158(4) A°, a = 80.931(1)°, ß = 81.772(2)°, ? = 80.691(1)°; 3, a = 9.3399(2) A°, b = 9.8796(2) A°, c = 19.0494(4) A°; a = 81.037(1)°, ß = 81.808(1)°, ? = 80.736(1)°. 1 and 3 consist of two octahedral differently charged cluster entities, [Ta6Br12]2+ in the [Ta6Br12(H2O)6]2+ cation and [Ta6Br12]4+ in trans-[Ta6Br12(OH)4(H2O) 2]. Average bond distances in the [Ta6Br12(H2O)6]2+ cations: 1, Ta-Ta, 2.9243 A°; Ta-Bri, 2.607 A°; Ta-O, 2.23 A°; 3, Ta-Ta, 2.9162A°; Ta-Bri, 2.603 A°; Ta-O, 2.24 A°. Average bond distances in trans-[Ta6- Br12(OH)4(H2O)2]: 1, Ta-Ta, 3.0133 A°; Ta-Bri, 2.586 A°; Ta-O(OH), 2.14 A°; Ta-O(H2O), 2.258(9) A°; 3, Ta-Ta, 3.0113 A°; Ta-Bri, 2.580 A°; Ta-O(OH), 2.11 A°; Ta-O(H2O), 2.13(1) A°. The crystal packing results in short O?O contacts along the c axes. Under the same experimental conditions, [Ta6Cl12]2+ oxidized to [Ta6Cl12]4+, whereas [Nb6X12]2+ clusters were not affected by the Cu2+ ion.
Organisation(s): Department of Mineralogy and Crystallography
External organisation(s): Rudjer Boskovic Institute
Journal: Zeitschrift für Anorganische und Allgemeine Chemie
Volume: 628
Pages: 401-408
No. of pages: 8
ISSN: 0044-2313
Publication date: 2002
Peer reviewed: Yes
Austrian Fields of Science 2012: 1051 Geology, Mineralogy
Portal url: https://ucrisportal.univie.ac.at/en/publications/77797de8-6d07-4efe-a79f-4645a5ec5676

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