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1,2,4-Triazole Complexes XII * Magnetic properties ol Fe ( 1, 2, 4-triazole)2 ( NCS)2, a quasi two-dimensional S = £. antiferromagnet with hidden canting.

D. W. Engelfriet, W. L. Groeneveld
Department Inorganic Chemistry , Gorlaeus Laboratoria,
Rijksuniversiteit, Leiden, The Netherlands
and G. M. Nap
Kamerlingh Onnes Laboratorium,
Rijksuniversiteit , Leiden , The Netherlands
Z. Naturforsch. 85a, 852-864 (1980);

[received June 12 1980]

Fe(trz)2(NCS)2 has been investigated by means of magnetic susceptibility and magnetization measurements on single crystals at temperatures 1.8—300 K, heat capacity measurements at 1.5—90 K and neutron powder diffraction at 1.2 K. The compound orders antiferromagnetically at T c — 8.46(2 ) K. The susceptibilities along the orthorhombic axes are strongly anisotropic, the a axis being the preferred direction. The susceptibility data along a and the heat capacity results are in reasonable agreement with the predictions for the quadratic layer, S = J. Ising antiferromagnet, with an intralayer exchange constant J Ik = — 7.2(2 ) K. Below T c the magnetization curve along the a axis reveals a metamagnetic transition at 1.74 kOe. In accordance with the Ising-like properties, a direct transition from the antiferromagnetic to the paramagnetic state is observed along a at 50 kOe. Hidden canting is found to be present. At 1.2 K the compound appears to be monoclinically distorted with a = 88.3° ( with respect to Aba2, the space group at 300 K ). The magnetic structure consists probably of four sublattices with the magnetic moments lying in the planes z = 0 and z = J ( with respect to the distorted cell in Aba2 ) along directions that are at an angle of 8° with the a axis. Ligand bonding parameters are discussed in terms of the angular overlap model.

Introduction