A high yield route to rhenium(VII) bis(imido) neopentylidene complexes

Article abstract of DOI:10.1021/om00147a038

The reaction between ReO₃(OSiMe₃) and ArNCO (Ar = 2,6-diisopropylphenyl) yields what is believed to be a mixture of Re₂O_x (NAr)_7-x complexes, one of which, Re₂O₂(NAr)₅ (1), can be isolated in ～30% yield. Pure 1, or the crude mixture, when treated with 3 equiv of py·HCl (py = pyridine) yields Re(NAr)₂(Py)Cl₃ (2) in 70-80% isolated yield vs. ReO₃(OSiMe₃). Addition of 0.65 equiv of Zn(CH₂-t-Bu)₂ to 2 yields Re(NAr)₂(CH₂-t-Bu)Cl₂ (3) in 75% isolated yield. Dehydrohalogenation of 3 with DBU yields Re(NAr)₂(CH-t-Bu)Cl (4) virtually quantitatively, which can be treated with LiOR (OR = OCH(C-F₃)₂ or O-2,6-C₆H₃-i-Pr₂) to give relatives of the type Re-(NAr)₂(CH-t-Bu)(OR) (5). Compounds 4 and 5 are very soluble, presumably monomeric, 18-electron complexes that do not react with cis-2-pentene or norbornene.