Electron transfer induced magnetic ordering of metal-cyanide magnets

After over three decades of intense research effort, molecular cyanide magnets offer the prospect of low-temperature solution growth and stimuli-dependent magnetic properties. Central to the magnetic properties of cyanide compounds, electron transfer and spin coupling of structural cyanide networks are crucial because they control the magnetic ordering characteristics. However, the candidates of magnetically ordered molecules with controlled electron transfer are still very rare. Here we report atomic coordination induced control of electron transfer in solution grown metal-cyanide magnets, where the 2D FeSe layered material can react with the cyanide-chain dependent electron-accepting molecules, 7,7,8,8-tetracyanoquinodimethane and tetracyanoethylene. We demonstrate the electron transfer in Fe:cyanide networks, revealing its striking role in the magnetization and magnetic ordering. This study opens up a new avenue to design coordination magnets with high-temperature magnetic properties. Solution synthesis of molecular cyanide magnets via FeSe template is promoted by thermal activation, where TCNE molecules substitute Se atoms in two-dimensional FeSe framework.