Multiple C–H Bond Cleavage of the Alkyl Group in (2,6-Dialkylphenoxo)ruthenium(II) Complexes

The
metathetical reaction between cis-RuCl2(PMe3)4 and an excess amount of potassium
2,6-dimethylphenoxide rapidly produces an oxaruthenacycle by the sp3 C–H bond cleavage reaction of the o-methyl group. With potassium 2,6-diethyl- and 2,6-diisopropylphenoxides,
multiple C–H bond cleavage of o-alkyl groups
occurs to give unsaturated oxaruthenacycles. These multiple activations
are triggered by the sp3 C–H bond cleavage of the o-alkyl group from bis­(2,6-dialkylphenoxo)­ruthenium­(II)
to form a saturated ruthenacycle followed by β-hydride elimination
and dehydrogenation from the resulting (2-alkenyl-6-alkylphenoxo)­(hydrido)­ruthenium­(II)
intermediate.