Reactivity of Paramagnetic Fe-II-Bis(amidinate) Complexes

Synthesis and characterisation of ether adducts of bis(amidinate) Fe-II complexes are described [amidinate = 2,6-iPr(2)C(6)H(3)-NC(Ph)N-Ph]. The isolation of these five-coordinate complexes contrasts with the homoleptic bis(amidinate) Fe complexes obtained previously with the sterically more demanding amidinate ligands 2,6-iPr(2)C(6)H(3)-NC(Ph)N-Ar (Ar = 2,6-iPr(2)C(6)H(3), 2,6-Me2C6H3) The more accessible ether adducts show enhanced reactivity towards Lewis bases and towards the pi-acid carbon monoxide. Reaction with excess amounts of CO results in carbonyl insertion into the Fe-N bonds, thereby giving rise to a diamagnetic bis(CO) adduct supported by two carbamoyl ligands.