The chemistry of rhenium alkyls. Part III. The synthesis and reactions of hexamethylrhenium(VI), cis-trimethyldioxorhenium(VII), and the octa-methylrhenate(VI) ion

The green, crystalline, paramagnetic (d1) hexamethylrhenium, ReMe6, has been prepared by interaction of tetramethyloxorhenium(VI), ReOMe4, with trimethylaluminium. It is characterised by mass, i.r., and e.s.r. (reported separately) spectra. It reacts with dioxygen to give ReOMe4 and with nitric oxide to give cis-trimethyldioxorhenium(VII), ReO2Me3: the latter is best prepared by the action of NO on ReOMe4. The mechanism of this reaction is discussed and an intermediate of stoicheiometry ReO(CH3)3(CH3NO) is characterised. N.m.r. spectra of the oxo-species are reported.Interaction of hexamethylrhenium with methyl-lithium forms the octamethylrhenate(VI) ion, which can be isolated as the tetramethylethylenediamine (tmed) salt Li2[ReMe8]·tmed.An improved synthesis of ReOMe4 is given.