Occurrence of a Rare 49·66 Structural Topology, Chirality, and Weak Ferromagnetism in the [NH4][MII(HCOO)3] (M = Mn, Co, Ni) Frameworks
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- 作者：Zheming Wang ; Bin Zhang ; Katsuya Inoue ; Hideki Fujiwara ; Takeo Otsuka ; Hayao Kobayashi ; Mohamedally Kurmoo
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：January 22, 2007
- 年：2007
- 卷：46
- 期：2
- 页码：437 - 445
- 全文大小：259K
- 年卷期：v.46,no.2(January 22, 2007)
- ISSN：1520-510X
文摘
We report the synthesis, crystal structures, thermal, IR, UV-vis, and magnetic properties of a series of divalenttransition metal formates, [NH4][M(HCOO)3], where M = divalent Mn, Co, or Ni. They crystallize in the hexagonalchiral space group P6322. The structure consists of octahedral metal centers connected by the anti-anti formateligands, and the ammonium cations sit in the channels. The chiral structure is a framework with the rarely observed49·66 topology, and the chirality is derived from the handedness imposed by the formate ligands around the metalsand the presence of units with only one handedness. The thermal properties are characterized by a decompositionat ca. 200 
C. The three compounds exhibit an antiferromagnetic ground state at 8.4, 9.8, and 29.5 K for Mn, Co,and Ni, respectively. The last two display a weak spontaneous magnetization due to a small canting of the momentsbelow the critical temperature, and the Co compound shows a further transition at lower temperatures. The isothermalmagnetizations at 2 K show spin-flop fields of 600 Oe (Mn), 14 kOe (Co), and above 50 kOe (Ni) and a smallhysteresis with a remnant magnetization of 25 cm3 G mol-1 (Co) and 50 cm3 G mol-1 (Ni) and coercive field of400 Oe (Co) and 830 Oe (Ni).
C. The three compounds exhibit an antiferromagnetic ground state at 8.4, 9.8, and 29.5 K for Mn, Co,and Ni, respectively. The last two display a weak spontaneous magnetization due to a small canting of the momentsbelow the critical temperature, and the Co compound shows a further transition at lower temperatures. The isothermalmagnetizations at 2 K show spin-flop fields of 600 Oe (Mn), 14 kOe (Co), and above 50 kOe (Ni) and a smallhysteresis with a remnant magnetization of 25 cm3 G mol-1 (Co) and 50 cm3 G mol-1 (Ni) and coercive field of400 Oe (Co) and 830 Oe (Ni).