Structure of a Carbon Monoxide Adduct of a “Capped” Porphyrin: Fe(C2-Cap)(CO)(1 -methylimidazole)

Kimoon Kim, James A Ibers*

*Corresponding author for this work

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Abstract

The structure of Fe(C2-Cap)(CO)(1-MeIm) has been determined by single-crystal X-ray diffraction methods. It consists of the packing of two crystallographically independent porphyrin molecules and solvate molecules. Both porphyrin molecules display the expected connectivity in which the benzene caps are slanted with respect to the mean porphyrin planes (dihedral angles of 15.5 and 11.5° for molecules 1 and 2, respectively). The centroids of the cap atoms are 5.57 and 5.68 A from the mean porphyrin planes. Since this distance is 3.96 Å in H2(C2-Cap), the cap moves 1.6–1.7 Å further away from the porphyrin upon binding a CO ligand inside the cavity. The coordinated CO ligand is slightly but detectably distorted from linearity, being both bent and tilted off the axis normal to the porphyrin. The Fe-C-O bond angle and the off-axis displacements for the C and 0 atoms of CO are 173.1 (9)°, 0.17 Å, and 0.41 Å, respectively, for molecule 1, and 175.8 (8)° and 0.12 and 0.28 Å, respectively, for molecule 2. Crystallographic data: triclinic P1, Z = 4, a = 18.022 (2) Å, b = 20.017 (1) Å, c = 20.691 (2) Å, α = 70.507 (7)°, β = 76.232 (10)°, γ = 82.549 (7)° at −150 °C, 18 468 observations, 1740 variables, R(F) = 0.096 (Fo 2 > 3σ(Fo 2)).

Original languageEnglish (US)
Pages (from-to)6077-6081
Number of pages5
JournalJournal of the American Chemical Society
Volume113
Issue number16
DOIs
Publication statusPublished - Jul 1 1991

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ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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