Magnetochemistry of the tetrahaloferrate(III) ions. 6. Crystal structure and magnetic ordering in [(pyH)3Cl][FeCl4]2

✍ Scribed by Roey Shaviv; Carol B. Lowe; Jalal A. Zora; Christer B. Aakeröy; Peter B. Hitchcock; K.R. Seddon; Richard L. Carlin

• Book ID: 104138792
• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 984 KB
• Volume: 198-200
• Category: Article
• ISSN: 0020-1693
• DOI: 10.1016/s0020-1693(00)92405-8

✦ Synopsis

The crystal structure, magnetic susceptibilities and specific heat of the title compound were determined by Xray diffraction, susceptometry between 1.2 and 20 K, and adiabatic calorimetry between 1.5 and 39 K, respectively. The material is found to be a canted antiferromagnet with a critical temperature of 2.212 K. A A-feature in the heat capacity at that temperature and an apparent break in the susceptibility curves are indicative of the manifestation of long-range order. A large degree of short-range order is observed to persist above the critical temperature, however. The compound crystallizes in the orthorhombic space group Pbca (Z= 8 a =13.040( ), b = 15.929(2), c=27.014(5) A and V=5611.2 A3). Bond lengths average 2.184(5) and 2.185(2) 8, for Fe(ljC1 and Fe(2)-Cl, respectively, within the slightly distorted tetrahedra. Single crystal magnetic susceptibility measurements of the sample show behavior consistent with that of a three-dimensional Heisenberg antiferromagnet with a small ferromagnetic peak whose maximum is identified at 2.00(l) K. This behavior is indicative of sublattice canting. A fit of the data from high temperature series expansions for a Heisenberg S=5/2 simple cubic lattice gives jq/kn = 0.084( 1) K with g = 2.00.