Magnetic Studies on Hexahalorhenate(IV) Salts of Ferrocenium Cations [Fe(C<sub>5</sub>R<sub>5</sub>)<sub>2</sub>]<sub>2</sub>[ReX<sub>6</sub>] (R = H, CH<sub>3</sub>; X = Cl, Br, I)
收藏资源简介：
The hexahalorhenate(IV) salts of formula [Fe(C5H5)2]2[ReX6], with X = Cl (1), Br (2), and I (3), and [Fe(C5Me5)2]2[ReX6], with X = Cl (4), Br (5), and I (6) ([Fe(C5Me5)2]+ = decamethylferrocenium cation), have been synthesized and the structures of 1, 2, and 4 determined by single-crystal X-ray diffraction. 1, 2, and 4 crystallize in the orthorhombic system, space groups Pbca (1 and 2) and Ibam (4), with a = 14.099(2) Å, b = 16.125(2) Å, and c = 22.133(15) Å, for 1, a = 14.317(3) Å, b = 16.848(3) Å, and c = 22.099(2) Å for 2, and a = 15.8583(5) Å, b = 15.9368(5) Å, and c = 16.9816(6) Å for 4. The three structures are made up of discrete [ReX6]2- anions and ferrocenium cations held together by electrostatic forces. There are anion−anion contacts in 1 and 2 but only through one direction. The [ReX6]2- octahedra are arranged along the y axis forming chains of Re and X atoms, −Re−X···X−Re−X···X−Re−, where the intermolecular X···X distances are shorter than the van der Waals distances. A somewhat greater separation between the anions occurs in 4. The magnetic properties of 1−6 were investigated in the temperature range 2.0−300 K. 1, 2, 4, and 5 exhibit an antiferromagnetic coupling between the anions, whereas a ferromagnetic coupling between anions and cations is the dominant interaction in 3. 6 behaves as a magnetically isolated compound, its susceptibility being the simple addition of the independent contributions of the uncoupled paramagnetic cations and anions.
