 Silylation of the aryloxyiminoquinonate ligand in Pb(ONOQ)2 with chlorosilanes RSiX2Cl (R = Me, Ph; X = Me, Ph, Cl) results in pentacoordinate silicon compounds (ON[R]O)SiX2 with a reduced, dianionic amine-bisphenolate ligand in which the methyl or phenyl group has migrated to nitrogen.  Methyl migration is observed exclusively over phenyl migration, though phenyl migration is observed if no alkyl groups are present. An analogous reaction of methyltrichlorostannane, MeSnCl3,with Pb(ONOQ)2 results in an octahedral unmigrated product, whereas methyltrichlorosilane reacts via methyl migration and the formation of a reduced aminebisphenoxide as shown. Computational studies suggest significantly higher barriers for methyl migration from tin than from silicon (??G� > 14 kcal mol-1), in good agreement with the > 1010-fold higher rate for silicon observed experimentally. This study may provide insights into how to activate the normally unreactive silicon-carbon bond for use as a less toxic alternative source of carbon nucleophiles.

Can silicon act as a substitute for tin? Alkyl and aryl migrations from Si/Sn to nitrogen in hypervalent iminoquinonate complexes

246th National Meeting (2013)

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