<p>There
is a large interest in developing oxidative transformations catalyzed by
palladium complexes that employ environmentally friendly and economical
oxidizing reagents such as dioxygen. Recently, we have reported the isolation
and characterization of various mononuclear Pd<sup>III</sup> and Pd<sup>IV</sup>
complexes supported by the tetradentate ligands <i>N,N’</i>-di-alkyl-butyl-2,11-diaza[3.3](2,6)pyridinophane (<sup>R</sup>N4,
R = <sup>t</sup>Bu, <sup>i</sup>Pr, Me), and the aerobically-induced C-C and
C-heteroatom bond formation reactivity was investigated in detail. Given that
the steric and electronic properties of the multidentate ligands were shown to
tune the stability and reactivity of the corresponding high-valent Pd complexes,
herein we report the use of an asymmetric N4 ligand, <i>N-</i>mehtyl-<i>N’</i>-tosyl-2,11-diaza[3.3](2,6)pyridinophane
(<sup>TsMe</sup>N4), in which one amine N atom
contains a tosyl group. The N-Ts donor atom exhibits a markedly reduced
donating ability, which led to the formation of transiently stable Pd<sup>III</sup>
and Pd<sup>IV</sup> complexes, and consequently the corresponding O<sub>2</sub>
oxidation reactivity and the subsequent C-C bond formation was improved
significantly.</p>
C−N Bond Formation from a Masked High-Valent Copper Complex Stabilized by Redox Non-Innocent Ligands
