Methyl transfer reactivity of pentachloromethylplatinate(IV) anion with a series of N-nucleophiles

Publication date: Available online 26 October 2018Source: Journal of Organometallic ChemistryAuthor(s): Daniel J. Adams, Brian Johns, Andrei N. VedernikovAbstractReactivity of K2[PtIVCH3Cl5] toward a series of substituted N,N-dimethylanilines 1a-1g, N,N-diisopropylaniline 1h and 2,6-substituted pyridines 2a-2b was investigated in 60% (vol.) aqueous acetone solutions. The reactions result in corresponding N-methylammonium or N-methylpyridinium products, 3 or 4, with high selectivity for the substrates 1a-1g and 2b, and follow an overall 2nd order kinetics, 1st order in both the PtIV complex and the amines. The reactivity is discussed in terms of the amine electronic properties and steric bulk. For the series of N,N-dimethylanilines 1a-1g, Me2NC6H4R (R = H, m-Cl, p-Cl, m-Me, p-Me, p-MeO, p-Me2N), a high quality linear correlation was found between logarithm of the reaction second order rate constant, log(k2), and pKa of the anilines. At the same time, the reactivity of the bulkier N,N-diisopropylaniline substrate 1h is about 3 orders of magnitude lower than predicted using this correlation. Finally, the pyridines 2a-2b are 3–4 orders of magnitude less reactive than N,N-dimethylanilines of similar pKa. Interestingly, the reactivity of K2[PtIVCH3Cl5] toward N,N-dimethylanilines is of the same order of magnitude or slightly greater than that of a standard organic methylating agent, dimethylsulfate Me2SO4. A computational (DFT) modeling of the title reaction is consistent wit...

Source: Journal of Organometallic Chemistry - October 27, 2018 Category: Chemistry Source Type: research