Ab initio molecular orbital calculations on square-pyramidal iron nitrosyls. Geometry and electronic structure of {FeNO}6, {FeNO}7, and {FeNO}8 systems Academic Article uri icon


  • Ab Initio molecular orbital calculations at several Fe-N-0 bond angles are reported for [Fe(CN)4NO]n- (n = 1-3) and for [Fe(CO)2(CN)2NO]−. An important energetic contribution to the linear geometry of the {FeNO} 6 species arises from interaction of the filled nitrosyl 5σ and Iπ orbitals with the metal in addition to the interaction of the nitrosyl 2π orbital. The potential energy curve for the {FeNO} 7 system is nearly flat in agreement with the wide variety of experimental geometries and with a poorly defined oxygen position in many X-ray structures for {MNO} 7 systems. The ground state of this ion, [Fe(CN)4NO]2-, is predicted to be a linear 2A1 state with considerable unpaired density in a 3dz2 orbital in agreement with the X-ray structure, Müssbauer, and EPR data. The {FeNO} 8 species show the expected bent geometry. The tendency for the nitrosyl to bend in the plane of the better π acceptor (CO plane in [Fe(CO)2(CN)2NO]−) is confirmed, and a simple electrostatic rationale for this behavior is presented. © 1980, American Chemical Society. All rights reserved.

author list (cited authors)

  • Hawkins, T. W., & Hall, M. B.

citation count

  • 11

publication date

  • June 1980