Abstract
A homoleptic organometallic Fe(IV) complex that is stable in both solution and in the solid state at ambient conditions has been synthesized and isolated as [Fe(phtmeimb)(2) ](PF(6) )(2) (phtmeimb=[phenyl(tris(3-methylimidazolin-2-ylidene))borate](-) ). This Fe(IV) N-heterocyclic carbene (NHC) complex was characterized by (1) H NMR, HR-MS, elemental analysis, scXRD analysis, electrochemistry, Mößbauer spectroscopy, and magnetic susceptibility. The two latter techniques unequivocally demonstrate that [Fe(phtmeimb)(2) ](PF(6) )(2) is a triplet Fe(IV) low-spin S=1 complex in the ground state, in agreement with quantum chemical calculations. The electronic absorption spectrum of [Fe(phtmeimb)(2) ](PF(6) )(2) in acetonitrile shows an intense absorption band in the red and near IR, due to LMCT (ligand-to-metal charge transfer) excitation. For the first time the excited state dynamics of a Fe(IV) complex was studied and revealed a ≈0.8 ps lifetime of the (3) LMCT excited state of [Fe(phtmeimb)(2) ](PF(6) )(2) in acetonitrile.