[FENO]7, AND [FENO]8 SYSTEMS ABINITIO MOLECULAR-ORBITAL CALCULATIONS ON SQUARE-PYRAMIDAL IRON NITROSYLS - GEOMETRY AND ELECTRONIC-STRUCTURE OF [FENO]6

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 5 and I orbitals with the metal in addition to the interaction of the nitrosyl 2 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, Mssbauer, 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 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.

ABINITIO MOLECULAR-ORBITAL CALCULATIONS ON SQUARE-PYRAMIDAL IRON NITROSYLS - GEOMETRY AND ELECTRONIC-STRUCTURE OF [FENO]6, [FENO]7, AND [FENO]8 SYSTEMS Academic Article