Spin-crossover (SCO) complexes of 3d4-3d7 transition metal ions offer an appealing combination of magnetic bistability and synthetic tunability. Nevertheless, the latter factor requires a careful consideration to ensure that the modification of ligands around the metal center does not compromise the ligand field strength and the feasibility of spin transition. In this vein, we have demonstrated that 2,2'-biimidazole (BIM) offers a convenient platform for modification of Fe(II) SCO complexes. The ligand can be conveniently alkylated at the protonated nitrogen atoms, preserving essentially the same ligand filed strength, as shown by a study of tris-chelated Ni(II) complexes of BIM and its alkylated derivatives. We report our studies of a number of Fe(II) SCO complexes with these ligands, including the observation of SCO with thermal hysteresis, solvent- and anion-dependent SCO, and photoinduced spin transitions known as light-induced excited spin state trapping (LIESST).

Alkylated biimidazoles as efficient ligand platform for functionalized Fe(II) spin-crossover complexes

244th National Meeting (2012)

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