A New Mode of Reactivity for Pyridine <i>N</i>-Oxide: C−H Activation with Uranium(IV) and Thorium(IV) Bis(alkyl) Complexes

Uranium(IV) and thorium(IV) bis(alkyl) complexes of the type (C5Me5)2AnR2 (An = U, Th; R = CH3, CH2Ph) activate the sp2 and sp3 hybridized C−H bonds in pyridine N-oxide and lutidine N-oxide to produce the corresponding cyclometalated complexes, (C5Me5)2An(R)[η2-(O,C)-ONC5H4] and (C5Me5)2An(R)[η2-(O,C)-ON-2-CH2-5-CH3-C5H3]. These provide rare examples of C−H activation chemistry mediated by actinide metal centers. This chemistry is in contrast to the known oxygen atom transfer reactivity patterns of pyridine N-oxides with oxophilic metal complexes and constitutes a new mode of reactivity for pyridine N-oxides.