Resonance Raman and Infrared Spectra of Carbene Complexes of Iron Porphyrins Dongsheng Lu

Abstract

The resonance Raman and infrared spectra of four carbene complexes, Fe(TTP)CCl₂, Fe(TPP)¹³CCl₂, Fe(TPP)CBr₂ and Fe(TMP)CCl₂ were measured in the solid state. Based on normal coordinate calculations and observed isotopic shifts by CC1₂/¹³CC1₂ substitution, the v(Fe=C), v_a(CCl₂) and v_s(CCl₂) vibrations were assigned at 1274, 878 and 437cm⁻¹, respectively. The bromo analogue exhibits these bands at 1270,823 and 364 cm⁻¹, respectively. All TPP complexes exhibit the spin-state sensitive band (v₂) at 1569 cm⁻¹ and the oxidation-state sensitive band (v₄) at 1370cm⁻¹, thus suggesting that the Fe atoms in these carbene complexes are low-spin Fe(IV).

Key Words:

• Carbene complexes of iron porphyrins