Reactivity of cationic isocyanide iron(II) derivatives towards nucleophilic agents

Abstract

Attack of MeNH2 on two adjacent isocyanide ligands in [Fe(dppe)(CNPh)4](ClO4)2 (Ia) gives ▪ (II). II reacts with concentrated aqueous HClO4 to give ▪ (III), which contains a chelating diaminocarbene ligand. Refluxing of a dichloromethane solution of III causes opening of the carbene ring to give mer-[Fe(dppe)(CNPh)3{C(NHPh)(NHMe)}](ClO4)2 (IV). Treatment of III or IV with KOH complex regenerates II. Ia also undergoes addition of Me2NH to give ▪ (V). Reaction of the complexes [Fe(dppe)(CNR)4](ClO4)2 (Ia: R = phenyl; Ib: R = 4-methylphenyl) with KOH gives the carbonyl derivatives ▪ (VIa and VIb). Treatment of VIa with dilute aqueous HClO4 yields ▪ (VII), which takes up a second proton when treated with concentrated aqueous HClO4 to give trans-[Fe(dppe)(CNPh)2(CO){C(NHPh)2}](ClO4)2 (VIII).