Insertion of Molecular Oxygen into the Metal–Methyl Bonds of Platinum(II) and Palladium(II) 1,3-Bis(2-pyridylimino)isoindolate Complexes

Abstract

Upon exposure of [(BPI)M(CH 3 )] (M = Pd, Pt, BPI = 1,3-bis(2-pyridylimino)isoindole) complexes to O 2 , direct insertion was observed to generate the O 2 insertion products (BPI)M(OOCH 3 ). Kinetic and mechanistic analyses of the O 2 insertion reaction support a radical chain substitution mechanism. Reproducible kinetics were observed in the presence of a radical initiator. The release of methanol was subsequently observed from the M−OOCH 3 products.

Photolytic Activation of Late-Transition-Metal–Carbon Bonds and Their Reactivity toward Oxygen

“…The hydroxo complex [Pt­( BPI )­OH] was prepared independently by reacting the chloro complex with excess KOH in THF under reflux, and the NMR spectrum confirmed the assignments (see the Supporting Information). Similar hydroxo complexes of platinum­(II) with BPI ligands were recently reported by Goldberg, and their spectroscopic features correspond to those seen here …”

“…This distortion is likely due to steric repulsion with the hydrogen atoms at the ortho position of the pyridine rings. Similar distortions were seen in the recently reported related BPI Pt­(II) and Pd­(II) methyl complexes by Goldberg . It is worth noting that out-of-plane distortions with N–M–C angles of approximately 167° have been seen previously in our studies on oxygen insertion reactions with 6,6″-disubstituted terpyridine Pt­(II) and Pd­(II) methyl complexes …”

“…After 20 min, the Pt–Me signal at 1.04 ppm disappeared and a new singlet peak was seen at 3.94 ppm, which corresponds to the methylperoxo complex [Pt­( BPI )­OOMe] (see Figure S11 and Scheme ). The spectroscopic features of this methylperoxo complex are very similar to those seen for the methylperoxo BPI complexes reported by Goldberg . The protons at the 6-position of the pyridines are strongly deshielded at 10.44 ppm (cf.…”

“…Indeed, the electronic and photophysical properties of Pt­(II) and Pd­(II) BPI complexes with a range of additional ligands have been investigated in great detail. − Goldberg recently reported the oxygen insertion of Pt­(II) and Pd­(II) methyl complexes with BPI -type ligands to give methylperoxo complexes (see Figure ). Kinetic studies with AIBN as an initiator indicated a radical chain mechanism for the oxygen insertion process. Noteworthy in this context are also the earlier studies on cobalt­(III) alkylperoxy complexes with BPI ligands that have been applied in the photoinduced oxidation of hydrocarbons. − The oxygen insertion with a related nickel­(II) methyl complex to give a methylperoxo complex, as shown in Figure , is also relevant in this context …”

Formate-driven catalysis and mechanism of an iridium–copper complex for selective aerobic oxidation of aromatic olefins in water

“…Finally, the heterolysis of the O-O bond gives the corresponding methyl ketone and the initial Ir(H)-Cu complex is regenerated from formic acid. The metal-alkylperoxido species formed by the O 2 insertion into the metal-alkyl bond has been previously reported [49][50] and was also proposed as a reaction intermediate in Wacker-type oxidations of olefins. 31,32 The DFT-optimized structure and the electronic properties of Ir(OOEtBnS)-Cu are shown in Fig.…”