SYNTHESIS OF NEW MIXED-ALKYL RHENIUM(VII) ORGANOIMIDO COMPLEXES AND ANEW FACILE ROUTE TO ME3SIORE(NBUT)3

Alkylation of the rhenium(VII) dichloro compound of the formula MeRe(N R')2 Cl2PY (1) with MeMgCl, Et2Zn and Pr(i)MgCl yields the d0 trialkyl diimido complexes of the formula MeR2Re(NR')2 (2a-c) (R=Me, Et, Pr(i) ; R'=2,6-dimethylphenyl). Compound 2a is stable at 25-degrees-C, while compounds 2b and c decompose within a few hours. In a similar manner the alkylation of the new tert-butyl imido derivative MeRe (NBu(t))2Cl 2 (4) [prepared from MeRe(NBu(t))3 (3) by hydrochlorination] yields th e tri-alkyl complexes of the formula MeR2Re(NBu(t))2 (5a-c) (R = Me, E t and Pr(i)), of which the mixed-alkyl species are again thermolabile. Analysis of the gas-phase decomposition products revealed a rather co mplex decomposition pathway, in which the beta-hydrogen elimination is likely to play a minor role. Reaction of the polymeric oxo species of the formula Me3SnOReO3 (6) with the silylamine Bu(t)NHSiMe3 gives, su rprisingly cleanly, the monomeric tris-imido compound of the formula M e3SiORe(NBu(t))3 (7) in 93% yield.