Synthesis, characterization and Pd(ii)-coordination chemistry of the ligand tris(quinolin-8-yl)phosphite. Application in the catalytic aerobic oxidation of aminesThis contribution is in memory of Dr Roberto A. Sánchez-Delgado (1950-2015), who dedicated his life to organometallic chemistry and catalysis (RIP).Electronic supplementary information (ESI) available: Experimental details, spectral and kinetic data and CIF files for ligand 2 and complex 3. CCDC 1547723 (2) and 1547722 (3). For ESI and

The synthesis and characterization of the ligand tris(quinolin-8-yl)phosphite, (P(Oquin) 3 ), are described and its coordination chemistry toward the metal precursor [Pd(COD)Cl 2 ] (COD = 1,5-cyclooctadiene, C 8 H 12 ) is reported. A new Pd( ii )-P(Oquin) 3 metal complex was isolated and fully characterized ([Pd{P(Oquin) 3 }Cl 2 ]), and its X-ray diffraction analysis shows that the phosphite ligand coordinates as a bidentate P-N chelate. This complex is an efficient catalyst for the solvent-free mild oxidative coupling of primary amines to imines using air as an oxidant, obtaining moderate to good yields (up to 99%) and turnover numbers (TONs up to 230). This catalyst can be recovered from the reaction mixture and reused in a subsequent run without a significant loss of activity. Kinetic measurements of the oxidation of benzylamine suggest that the rate law is r = k app [BnNH 2 ][cat] ([BnNH 2 ] = molar concentration of benzylamine, [cat] = molar concentration of [Pd{P(Oquin) 3 }Cl 2 ], k app = k [O 2 ] c = 0.756 L mol −1 h −1 = apparent rate constant). In situ NMR tests were performed to gain some insight into the reactivity of the Pd( ii )-P(Oquin) 3 complex toward benzylamine. The ligand P(Oquin) 3 is reported and was coordinated to Pd( ii ). This complex is a catalyst precursor for the homocoupling of amines.