Dramatic remote substituent effects on the electronic spin state of bis(scorpionate) iron(II) complexes.
Résumé
The purple-colored bis(tert-butylscorpionate) iron(II) complex is fully low-spin at room temperature, despite the steric hindrance brought about by the six methyl groups in the equatorial belt. The remotely situated bulky tert-butyl substituent on boron acts like a locking screw for a vise, forcing the tripod-shaped ligand to close, thus favoring low-spin complex formation.