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Iron and ruthenium carbonyls of 2,3,5,6-tetrakis(methylene)bicyclo[2.2.2]octane. Crystal and molecular structure of (C12H14)Fe(CO)3

1979; Elsevier BV; Volume: 35; Linguagem: Inglês

10.1016/s0020-1693(00)93439-x

1873-3255

A. Alan Pinkerton, G. Chapuis, Pierre Vogel, Ulrich Hänisch, Ph. Narbel, Tristano Boschi, Raymond Roulet,

Metal complexes synthesis and properties

The reaction of 2,3,5,6-tetrakis(methylene)bicyclo[2.2.2]octane (1a) with Fe2(CO)9 yields the two (η4-1,3-diene)Fe(CO)3 isomers (2: exo; 3:endo) together with two bimetallic isomers (C12H14)[Fe(CO)3]2 (4:endo-exo; 5:diexo). The reaction of 1a with Ru3(CO)12 yields the endo-(C12H14)Ru(CO)3 (6) and endo, exo-(C12H14[Ru(CO)3]2 (7) complexes as the main products. The molecular structure of 3 has been determined by X-ray crystallography. The Fe(CO)3 group is in the endo position with respect to the roof-shaped tetraene. The ligand is bound through one diene group to two basal positions of a tetragonal pyramidal Fe(CO)3L2 moiety. Hydrogen atom positions have been determined (final residual R = 0.029). The dimensions for the 1,3-butadieneirontricarbonyl system, as found in this and 41 other structures, are summarized and discussed statistically. In this study the weighted averages for all structures show the threeCC distances to be of equal length and the FeC (inner) distance to be shorter than the FeC (outer) distance. The deviations of H(Z) and H(E) atoms from the butadiene plane, as found in this and 6 other structures having an exocyclic unsubstituted 1,3-diene group, are also discussed. Neither thermal epimerization of iron nor epimerization catalyzed by H+ were found for complexes 2 – 7 whose structures in solution were deduced from their 1H and 13C NMR data on the basis of the known structure of 3.