Crystal structure of Tetracarbonyl(2,3-η-1,4-dihydro-1,4-epoxynaphthalene)iron(0)

The crystal structure of the title compound, [Fe(CO)₄(C₁₀H₈O)], has been determined at 295 K from diffractometer data, and refined by least squares to a residual of 0.073 for 2990 ‘observed’ reflections. Crystals are triclinic, Pī, a 22.980(6), b 9.385(3), c 6.313(2) Å, α 85.22(3), β 87.67(3), γ 79.48(3)°, Z4. The two independent molecules in the same cell differ only trivially in their geometries, the coordination number about the metal being essentially five: four carbonyls and the ethylene double bond in a pseudo-trigonal-bipyramidal arrangement. From distortions observed within the molecular geometry as a result of steric interactions between the epoxide oxygen and the nearby axial carbonyl, it clearly emerges that the stability of the present derivative relative to that of methylene bridged ligands is simply a consequence of the greatly increased stereochemical interaction of the latter and not of any electronic effect.