Fig. 5: Mechanistic investigations to identify features controlling catalyst activity.
From: Catalytic undirected methylation of unactivated C(sp3)−H bonds suitable for complex molecules
a Conversions of peroxides with varying loadings of Ir-F and Ni(acac)2. A higher loading of Ir-F leads to more rapid inactivation of the Ir-F toward activation of the peroxides, while the presence of Ni(acac)2 increases the lifetime of Ir-F. Investigations of the fate of Ir-F after the reaction, based on the mass spectra of the major peaks in the UV-vis trace of the LC chromatograms after the reactions. Monomethylated and dimethylated species of Ir-F were detected in the absence of Ni(acac)2. The picture depicts the difference in color of the two reaction mixtures at the end of the reaction with and without Ni(acac)2. b Monitoring the quantitative changes of 1a, 2a, and dicumyl peroxide over time. The termination of the formation of 2a after ~4 h, paired with the continued consumption of dicumyl peroxide and 1a after 4 h, suggest that the full deactivation of Ni(acac)2 occurs before the full deactivation of Ir-F. Ir-F = (Ir[dF(CF3)ppy]2(dtbpy))PF6; acac = acetylacetonate.
