Crystal Structure and Magnetic Properties of FeTe2O5X (X = Cl, Br): A Frustrated Spin Cluster Compound with a New Te(IV) Coordination Polyhedron
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- 作者：Richard Becker ; Mats Johnsson ; Reinhard K. Kremer ; Hans-Henning Klauss ; Peter Lemmens
- 刊名：Journal of the American Chemical Society
- 出版年：2006
- 出版时间：December 6, 2006
- 年：2006
- 卷：128
- 期：48
- 页码：15469 - 15475
- 全文大小：440K
- 年卷期：v.128,no.48(December 6, 2006)
- ISSN：1520-5126
文摘
A new layered transition metal oxohalide, FeTe2O5ClxBr1-x, has been identified. It crystallizes inthe monoclinic space group P21/c. The unit cell for FeTe2O5Br is a = 13.3964(8), b = 6.5966(4), c =14.2897(6) Å, 
= 108.118(6)
, and Z = 8. The layers are built of edge sharing [FeO6] octahedra forming[Fe4O16]20- units that are linked by [Te4O10X2]6- groups. The layers have no net charge and are only weaklyconnected via van der Waals forces to adjacent layers. There are four crystallographically different Teatoms, and one of them displays a unique [TeO2X] coordination polyhedron (X = Cl, Br). Magneticsusceptibility measurements show a broad maximum typical for 4-spin clusters of coupled Fe(III) ions inthe high-spin state. Evidence for magnetic instabilities exists at low temperatures, which have been confirmedwith specific heat experiments. A theoretical modeling of the susceptibility concludes a frustration of theintra-tetramer anti-ferromagnetic exchange interaction.
= 108.118(6), and Z = 8. The layers are built of edge sharing [FeO6] octahedra forming[Fe4O16]20- units that are linked by [Te4O10X2]6- groups. The layers have no net charge and are only weaklyconnected via van der Waals forces to adjacent layers. There are four crystallographically different Teatoms, and one of them displays a unique [TeO2X] coordination polyhedron (X = Cl, Br). Magneticsusceptibility measurements show a broad maximum typical for 4-spin clusters of coupled Fe(III) ions inthe high-spin state. Evidence for magnetic instabilities exists at low temperatures, which have been confirmedwith specific heat experiments. A theoretical modeling of the susceptibility concludes a frustration of theintra-tetramer anti-ferromagnetic exchange interaction.