Radical Stabilizing Ability of the Ferrocenyl and Cyclobutadieneiron Tricarbonyl Groups

Computational studies indicate that ferrocenyl-substituted methyl radicals owe their stability to a spin delocalization mechanism involving Fe and a major contribution from an eta(4) form. Cyclobutadieneiron tricarbonyl substituted methyl radicals are also calculated to be highly stabilized by spin delocalization onto Fe and a major contribution from an eta(3) form.