Chem. Mater. 2002, 14, 1201-1209
1201
Structural Distortions of the Metal Dichalcogenide Units in AMo2S4 (A ) V, Cr, Fe, Co) and Magnetic and Electrical Properties Paz Vaqueiro, M. Laura Kosidowski, and Anthony V. Powell* Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom Received August 7, 2001. Revised Manuscript Received January 2, 2002
Powder neutron diffraction data collected for AMo2S4 (A ) V, Cr, Fe, Co) reveal that the materials crystallize in the space group Cc (a ≈ 11.8 Å, b ≈ 6.5 Å, c ≈ 13 Å, β ≈ 114°). The structure consists of dichalcogenide (MS2) layers of edge-sharing octahedra, separated by a layer in which 50% of cation sites are occupied in an ordered fashion. Cations in the MS2 unit are distorted from an ideal hexagonal array. For the early transition series cations A ) Cr, V, the distortion involves the formation of triangular clusters of cations, whereas for A ) Fe, Co diamond-shape cation clusters are observed. The semiconducting properties of these materials are discussed in light of these results. Both FeMo2S4 and CoMo2S4 order antiferromagnetically with TN ) 110 and
