Two mononuclear nonheme FeIII complexes, [PPh4][FeIII(PS3′)(OCH3)] (1) and [PPh4][FeIII(PS3′)(Cl)] (2), supported by a tris(benzenethiolato)phosphine derivative PS3′ (PS3′ = P(C6H3-3-Me3Si-2-S)33-) have been synthesized and characterized. The structures resolved from X-ray crystallography show that FeIII centers in both complexes adopt distorted trigonal-bipyramidal geometry with a methoxide or a chloride binding in the axial position. The magnetic data for both are consistent with intermediate-spin FeIII centers with a C3 symmetry (S = 3/2 ground state). The bound methoxide in 1 is labile and can be replaced by a CH3CN molecule. The forming FeIII-CH3CN species can be further reduced by cobaltcene quantitatively to a stable FeII-CH3CN complex, [Fe(PS3′)(CH3CN)]-. One-electron oxidation of 2 by ferrocenium gave a FeIV analogue, [FeIV(PS3′)(Cl)]. Importantly, the FeIII-OCH3 moiety in complex 1 acts as a strong nucleophile that activates the C-Cl bond in CH2Cl2, leading to the formation of complex 2 quantitatively. Complex 1 also reacts with other electrophiles, benzyl chloride and benzyl bromide, to generate FeIII-X species (X = Cl or Br). The reactions were investigated and monitored by UV-vis-NIR, NMR, and ESI-MS spectroscopies.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Inorganic Chemistry