The four-coordinate iron(II) complex of the substituted octaazaannulene reported by Baldwin and Huff (J. Am. Chem. Soc., 95, 5757 (1973)) to be a molecular oxygen carrier has been characterized by a complete X-ray structural determination. The complex crystallizes with two molecules in space group C2h 5-P21/c of the monoclinic system in a cell of dimensions, a = 11.976 (8) Å, b = 8.147 (5) Å, c = 22.567 (14) Å, and β = 98.83(4)°. A crystallographic center of inversion is imposed on each molecule. The structure has been refined anisotropically to a final R index (on F) of 0.085 for the 2651 measured intensities having Fo 2 > 3σ(Fo 2). The coordination about the iron atom is approximately square-planar with two unequal Fe-N bond lengths of 1.846 (4) and 1.826 (4) Å. The bond lengths within the macrocyclic ligand are nearly identical with those observed in other octaazaannulene complexes, although the ligand is distinctly nonplanar in this complex. We believe the short Fe-N bond lengths in the complex result in part from the constrictive effect of the macrocycle.
ASJC Scopus subject areas
- Colloid and Surface Chemistry