Reaction of Pentadienyl Complexes with Metal Carbonyls:  Synthetic, Structural, and Theoretical Studies of Metallabenzene π-Complexes

The reaction of open and half-open sandwich complexes of iron and ruthenium with metal carbonyls was studied. Three types of complexes could be isolated:  Carbonyl-bridged iron−ruthenium dimers with cyclopentadienyl and pentadienyl terminal ligands, dimetallic iron carbonyl complexes with a bridging...

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Published in:Organometallics 2003-01, Vol.22 (2), p.264-274
Main Authors: Effertz, Ulrike, Englert, Ulli, Podewils, Frank, Salzer, Albrecht, Wagner, Trixie, Kaupp, Martin
Format: Article
Language:English
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Summary:The reaction of open and half-open sandwich complexes of iron and ruthenium with metal carbonyls was studied. Three types of complexes could be isolated:  Carbonyl-bridged iron−ruthenium dimers with cyclopentadienyl and pentadienyl terminal ligands, dimetallic iron carbonyl complexes with a bridging σ,π-coordinated pentadienyl ligand, and ruthenium complexes with one or two π-coordinated ruthenabenzene ligands. The latter are the first ever isolated bis(metallabenzene) π-complexes. The X-ray structures of C5Me5Ru(CO)4Fe(C7H11), (μ-C7H10)Fe2(CO)6, and [(C8H11)Ru(CO)3]2Ru are reported. Density functional calculations have been used to better understand the bonding in metallabenzene complexes. The electron localization function (ELF) clearly confirms metal−metal bonding interactions in the complexes studied. In particular, the bis(metallabenzene) complex 13 is found to exhibit a three-center bonding attractor in the ELF in its stable syn-eclipsed conformation but two two-center attractors in the ca. 30 kJ mol-1 less stable anti-eclipsed arrangement. The frontier orbitals of metallabenzenes exhibit very large participation of the ring metal. When metallabenzenes act as ligands to other metal fragments, direct metal−metal interactions are thus expected to be a general feature of the complexes, unless they are replaced by other interactions, e.g. by protonation. Natural population analyses suggest that the σ-donor abilities of the electron-rich d8 metallabenzene fragments predominate over their π-acceptor character.
ISSN:0276-7333
1520-6041
DOI:10.1021/om020789h