Isomerism in Bi-π-allyl type complexes
- 1 January 1968
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc. A
- p. 2248-2253
- https://doi.org/10.1039/j19680002248
Abstract
Reaction between Fe2(CO)9 and 1-phenylallene gave three isomeric complexes with the composition [PhCHCCH2 Fe(CO)3]2: (A) orange cubic crystals, m.p. 191–193°(B) orange-red prismatic crystals, m.p. 188–190°; (C) dark red prismatic crystals, m.p. 131–131·5°. On the basis of infrared and n.m.r. spectra, probable structures for these three are proposed. In (A), two isolated Fe(CO)3 moieties co-ordinate to a tetramethylene-ethene ligand whose double bond presumably participates in the co-ordination. In (B) and (C), the ligand may be regarded as a bi-π-phenylallyl to which the two Fe(CO)3 moieties, linked by a metal–metal bond, co-ordinate to the two allyl systems. (A) isomerised to (C) at 135° in o-dichlorobenzene, providing support for the structural assignment. In contrast to the parent bi-π-allyl complex, (B) and (C) do not show temperature-dependent tn.m.r. spectra. The isomerism or tautomerism is discussed, and a reaction scheme for formation of the three complexes is proposed.Keywords
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