Abstract
Neutral and cationic palladium complexes that bear pyridine ligands [i.e., pyridine (Py), 4‐ethylpyridine (4‐EtPy) and 2,4,6‐trimethylpyridine (2,4,6‐Me~3~Py)] have been isolated and characterized in solution by ^1^H and ^13^C{^1^H} NMR spectroscopy, cyclic voltammetry (CV) and in the solid state by elemental analysis and single‐crystal structure analysis. All palladium compounds have been scrutinized as a precursor to catalyze the aerobic oxidation of diols either in the presence or in the absence of an external base (i.e., K~2~CO~3~). As a result, the chemoselective production of the corresponding hydroxy ketones has been achieved. The bis‐cationic palladium complex of the formula Pd(4‐EtPy)~4~~2~ (OTs = p‐toluenesulfonate) [5b(OTs)~2~] emerged as the most promising precursor; it outperformed the neutral precursor that consisted of trans‐[Pd(OAc)~2~(4‐EtPy)~2~] (OAc = acetate) and 4‐EtPy [3b/2(4‐EtPy)] (2 mol‐equiv.). An operando high‐pressure (HPNMR) spectroscopic study with the precursor 5b(OTs)~2~ combined with the results obtained from catalytic reactions has provided insight into the catalytic mechanism that is operative in 5b(OTs)~2~‐catalyzed aerobic diol oxidation reactions.