Density functional theory of the iron–nitrosyl (S = 3/2) complex

On the basis of density functional theory (DFT), the iron–nitrosyl complex Fe[Me₃TACN](NO)(N₃)₂ (S = 3/2) is studied via the B3LYP hybrid method. Its Raman vibrational frequencies, atomic net charges, and spin densities are analyzed. The related complexes Fe(NH₃) (n = 1, 2, and 3) are employed as reference compounds to determine the characteristics of the central iron. Our results indicate that the S = 3/2 spin ground state of Fe[Me₃TACN](NO)(N₃)₂ is best described by the presence of Fe^II (S = 2) anti‐ferromagnetically coupled to NO⁰ (S = 1/2) yielding Fe^II[Me₃TACN](NO⁰)(N)₂. This is clearly different from the previous Fe^III‐NO^? theoretical assignment. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005