Iron-iron interaction through an ethanedithiolate ligand: a magnetic and theoretical study

The compound (CpFe(dppe)]₂μ-SCH₂CH₂SS,S′])(PF₆)₂ (1]PF₆]₂) has been synthesized and its magnetic properties have been investigated by susceptometer quantum interface device (SQUID) measurements in the temperature range 5-300 K. The d⁵-d⁵1²⁺ complex exhibits intramolecular antiferromagnetic behavior, with a magnetic coupling constant of −6.4 cm⁻¹. Density functional theory (DFT) calculations on a model of 1²⁺ (as well as on models of 1⁺ and 1) allow to determine its molecular structure and analyse its bonding and magnetic properties. The computed spin density exhibits significant localization on both the Fe and S centers. Replacing the heteroatoms of the bridging ligand by CH₂ groups leads to a relocalization of the spin density on the metal atoms and favors ferromagnetic coupling.