.eta.3 and .eta.6 Bridging cations in the N,N,N',N'',N''-pentamethyldiethylenetriamine-solvated complexes of benzylpotassium and benzylrubidium: an x-ray, NMR, and MO study

The metalation of toluene (PhCH 3 ) with a 1:1 mixture of n-BuLi/MO t Bu (M=K, Rb) at ambient temperature affords orange-red powders of benzylpotassium or benzylrubidium. On addition of N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDTA) the precipitates dissolve to give burgundy-red solutions, from which needles of [PhCH 2 K.PMDTA.0.5PhCH 3 ] n (1) or [PhCH 2 Rb-PMDTA] n (2) are obtained. X-ray analysis reveals that 1 incorporates half a molecule of toluene per asymmetric unit. In both 1 and 2, the η 3 and η 6 interaction of one M + cation with two benzyl fragments gives rise to the formation of polymeric chains. The coordination sphere of the cations is completed by one chelating triamine ligand