title: Quantitative geometric descriptions of the belt iron atoms of the iron-molybdenum cofactor of nitrogenase and synthetic iron(II) model complexes.
abstract: Six of the seven iron atoms in the iron-molybdenum cofactor of nitrogenase display an unusual geometry, which is distorted from the tetrahedral geometry that is most common in iron-sulfur clusters. This distortion pulls the iron along one C3 axis of the tetrahedron toward a trigonal pyramid. The trigonal pyramidal coordination geometry is rare in four-coordinate transition metal complexes. In order to document this geometry in a systematic fashion in iron(II) chemistry, we have synthesized a range of four-coordinate iron(II) complexes that vary from tetrahedral to trigonal pyramidal. Continuous shape measures are used for a quantitative comparison of the stereochemistry of the Fe atoms in the iron-molybdenum cofactor with those of the presently and previously reported model complexes, as well as with those in polynuclear iron-sulfur compounds. This understanding of the iron coordination geometry is expected to assist in the design of synthetic analogues for intermediates in the nitrogenase catalytic cycle.
authors.affiliation: Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
authors.forename: Javier
authors.initials: J
authors.lastname: Vela
authors.forename: Jordi
authors.initials: J
authors.lastname: Cirera
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Smith
authors.forename: Rene J
authors.initials: RJ
authors.lastname: Lachicotte
authors.forename: Christine J
authors.initials: CJ
authors.lastname: Flaschenriem
authors.forename: Santiago
authors.initials: S
authors.lastname: Alvarez
authors.forename: Patrick L
authors.initials: PL
authors.lastname: Holland
mesh_terms: D007501:Iron / Q000737:chemistry*; D046911:Macromolecular Substances / Q000138:chemical synthesis* / Q000737:chemistry; D008954:Models, Biological; D015394:Molecular Structure; D008983:Molybdoferredoxin / Q000737:chemistry*; D009591:Nitrogenase / Q000737:chemistry*
chemical_list: D046911:Macromolecular Substances; D008983:Molybdoferredoxin; D007501:Iron; D009591:Nitrogenase