Structural Distortion Controlled Spin-Crossover Behavior

Two mononuclear isomorphous complexes Fe­(<b>L1</b>)₂(SCN)₂ (<b>1</b>) and Fe­(<b>L2</b>)₂(SCN)₂ (<b>2</b>) [<b>L1</b> = 2-(pyridin-3-yl)-1<i>H</i>-imidazo­[4,5-<i>f</i>]­1,10-phenanthroline; <b>L2</b> = 2-(pyridin-4-yl)-1<i>H</i>-imidazo­[4,5-<i>f</i>]­1,10-phenanthroline] were obtained based on 1,10-phenanthroline derivatives. Due to the different structural distortion in the coordination geometries, <b>1</b> exhibits gradual spin transition around room temperature (<i>T</i>_1/2 = 315 K), while <b>2</b> displays a stable high-spin state