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An unusual near-eclipsed porphyrin ring orientation in two crystalline forms of ({mu}-oxo)bis[(octaethylporphinato)iron(III)]. Structural and molecular mechanics studies

Journal Article · · Inorganic Chemistry
;  [1]; ;  [2]
  1. Univ. of Notre Dame, IN (United States)
  2. Sandia National Lab., Albuquerque, NM (United States); and others

The structures of two polymorphs of ({mu}-oxo)bis[(octaethylporphinato)iron(III)], [Fe(OEP)]{sub 2}O (C{sub 72}H{sub 88}Fe{sub 2}N{sub 8}O), have been determined by X-ray structure analyses using data collected with an area detector. The two [Fe(OEP)]{sub 2}O polymorphs (a triclinic and a monoclinic form) show strong structural similarities. The eight Fe-N{sub p} bond distances have average values of 2.077(3) {Angstrom} in the triclinic form and 2.080(5) {Angstrom} in the monoclinic form. The average displacements of the iron(III) atom from the mean porphinato core are 0.50 {Angstrom} in the triclinic form and 0.54 {Angstrom} in the monoclinic form. The most important structural feature of the molecule in the two crystal forms is the near-eclipsed intramolecular porphyrin ring orientation: the average N-Fe-Fe{prime}-N{prime} dihedral angles are 17.0(10){degrees} in the triclinic form and 16.8(6){degrees} in the monoclinic form. Molecular mechanics calculations have been carried out to explore the inter-ring orientation; these suggest that peripheral ethyl group interactions lead to the near-eclipsed orientation. Crystal data: triclinic form, a = 11.561(5) {Angstrom}, b = 12.299(8) {Angstrom}, c = 23.341(16) {Angstrom}, {alpha} = 82.56(3){degrees}, {beta} = 81.94(7){degrees}, {gamma} = 79.18(1){degrees}, space group P1, V = 3210(5) {Angstrom}{sup 3}, Z = 2,8931 observed data, R{sub 1} = 0.050, R{sub 2} = 0.056; monoclinic form, a = 18.433(13) {Angstrom}, b = 15.104(6) {Angstrom}, c = 23.489(6) {Angstrom}, {beta} = 97.82(1){degrees}, space group P2{sub 1}/c, V = 6479(9) {Angstrom} {sup 3},Z = 4,6169 observed data, R{sub 1} = 0.054, R{sub 2} = 0.060.

Sponsoring Organization:
USDOE
OSTI ID:
458100
Journal Information:
Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 1 Vol. 34; ISSN 0020-1669; ISSN INOCAJ
Country of Publication:
United States
Language:
English