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  • When being straight bends rules: a rationale for the linear FeNO unit in the low-spin square-pyramidal {FeNO}7 tetracyanonitrosylferrate(2-) anion.

When being straight bends rules: a rationale for the linear FeNO unit in the low-spin square-pyramidal {FeNO}7 tetracyanonitrosylferrate(2-) anion.

Journal of inorganic biochemistry (2006-11-04)
Jeanet Conradie, Abhik Ghosh
ABSTRACT

All low-spin S=1/2 heme-NO complexes feature FeNO angles of about 140 degrees . In contrast, the square-pyramidal [Fe(CN)(4)(NO)](2-) complex features an exactly linear {FeNO}(7) unit. We have sought here to determine a possible, simple molecular orbital (MO) rationale for these structural variations. A DFT-based (DFT=density functional theory) MO analysis shows that the linearity of the latter stems from the greater pyramidalization of the Fe center, relative to nitrosylheme, which results in significant differences in d orbital hybridization. Thus, the singly occupied molecular orbital (SOMO) of [Fe(CN)(4)(NO)](2-) , while primarily Fe dz2-based, also has a significant amount of 4p(z) character, which makes it less stereochemically active, accounting for the linearity of the FeNO unit.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Iron(III) nitrate nonahydrate, BioReagent, suitable for cell culture
Sigma-Aldrich
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Supelco
Iron standard for AAS, analytical standard, 10.00 g/L Fe in nitric acid, traceable to BAM
Sigma-Aldrich
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