Syntheses and characterisation of methyltrioxorhenium adducts of low-valence organometallic Lewis bases

Abstract

Methyltrioxorhenium(VII) forms air and moisture stable trigonal-bipyramidal adducts with several organometallic Lewis bases having a pyridine nitrogen atom as the donor moiety. These complexes have been isolated and fully characterised. A single-crystal structure of one of the products has been determined. Whilst the Re–N interaction is weaker than in some simple organic Lewis base adducts of Re(CH₃)O₃, e.g. with pyridine or 4-tert-butylpyridine, the more pronounced stability of the complexes described in this work is probably due to steric crowding and the moderate donor capability of the organometallic ligands. The donor capability of the ligands applied increases in the order Re(CO)₃Br(4,4′-bpy)₂ < 1,1′-bis(4-pyridylethynyl)ferrocene < ferrocenyl-4-pyridylacetylene.