Bimetallic Iron(3+) Spin-Crossover Complexes Containing a 2,2′-Bithienyl Bridging bis-QsaIH Ligand

The multistep synthesis of a 2,2'-bithienyl bridging bis-QsalH ligand is described along with the preparation of four bimetallic iron(3+) spin-crossover complexes containing this ligand with different counteranions (Cl, PF6,SCN, and ClO4). In all four complexes, data from variable temperature magnetic susceptibility experiments and Mossbauer spectroscopy indicate that spin-crossover in these materials is gradual, incomplete, and occurs without thermal hysteresis. However, these complexes represent a rare example of bimetallic iron(3+) spin-crossover materials.