CRYSTAL AND MOLECULAR STRUCTURE OF (1,3,5-CYCLOOCTATRIENE)DIIRON HEXACARBONYL

The crystal and molecular structures of the compound (C8H10)Fe2(CO)6 obtained by reaction of cycloocta-l,3,5-triene with Fe2(CO)9 or Fe3(CO)12 have been determined by three-dimensional X-ray crystallographic techniques. The intensities of 1898 independent reflections were collected on a counter-diffractometer, and the structure was solved by Patterson and Fourier methods. Full-matrix, least-squares refinement was carried out using 1206 statistically significant reflections and employing anisotropic thermal parameters to give a final unweighted discrepancy index of 0.067. The compound crystallizes in space group P21/c. Unit cell dimensions are a = 13.39 ± 0.01 Å, b = 7.684 ± 0.004 Aring;, c = 14.31 ± 0.01 Aring;, β = 92.83 ± 0.04˚; density: ρ(obsd), 1.75 ± 0.01 g cm-1 ; ρ(calcd), assuming Z = 4, 1.75 g cm-1. The molecular structure is quite similar to that of (C8H8)Ru2- (CO)6, which we recently reported, and permits us to give the compound the systematic name cis-(l,2,6-trihapto: 3,4,5-trihaptocycloocta-1,3,5-triene)hexacarbonyldiiron. The molecule does not have a plane of symmetry and the metal atoms are not structurally equivalent, one Fe(CO)3 group being bound to three carbon atoms (3,4, 5) forming an allyl group while the other is bound to one carbon atom (6) by a two-center bond and to the olefinic group formed by two others (1, 2). The two Fe(CO)3 groups lie on the same side of the ring and are united by an Fe-Fe bond. © 1969, American Chemical Society. All rights reserved.