Comparing Metal–Halide and −Oxygen Adducts in Oxidative C/O–H Activation: Au(III)–Cl versus Au(III)–OH

High-valent metal−halides have come to prominence as highly effective oxidants. A direct comparison of their efficacy against that of traditional metal−oxygen adducts is needed. AuIII(Cl)(terpy)](ClO₄)₂ (1; terpy = 2,2′:6′,2-terpyridine) readily oxidized substrates bearing O−H and C−H bonds via a hydrogen atom transfer mechanism. A direct comparison with [AuIII(OH)(terpy) showed that 1 was a kinetically superior oxidant with respect to 2 for all substrates tested. We ascribe this to the greater thermodynamic driving force imbued by the Cl ligand versus the OH ligand.