Stereoselective dihapto-binding of prochiral aromatic compounds by {TpRe(CO)(PME3)}: Synthesis, characterization, stability, and enantiofacial discrimination (Tp = hydrido(tris)pyrazolylborate)

Synthetic access to {TpRe(CO)(PMe3)} and the ability of this fragment to bi nd unsaturated compounds are reported. A variety of complexes of the type T pRe(CO)(PMe3)(eta(2)-L) (L = cyclohexene, cyclopentene, naphthalene, phenan threne, thiophene, 2-methylthiophene, furan, or acetone) have been isolated and characterized, and stereochemical and stability issues of aromatic mol ecules bound to {TpRe(CO)(PMe3)} are discussed in detail. In particular, a solid-state structural study of TpRe(CO)(PMe3)(eta(2)-cyclohexene) has prov ided a foundation for a discussion of the stereoelectronic features of the Re(I) fragment, and substitution reactions of an aromatic ligand by acetone provide insight into the stability of these aromatic complexes. In additio n, a solid-state X-ray diffraction study of the Re(II) complex TpRe(CO)(PMe 3)(OTf) (OTf = trifluoromethanesulfonate) is presented.