Metallation of aliphatic carbon atoms. Part 1. Synthesis and characterization of the cyclopalladated complexes of 2-neopentylpyridine

Abstract

Metallation of the methyl group in 2-neopentylpyridine occurs with palladium(II) acetate to afford a novel six-membered cyclopalladated complex [{[graphic omitted])(O₂CMe)}₂]. This complex is readily converted into the chloro-bridged analogue, [{[graphic omitted])Cl}₂], by metathetical reaction with LiCl. The chloro-bridged complex undergoes bridge-splitting reactions with 3,5-dimethylpyridine and thallium(I) acetylacetonate to give the corresponding mononuclear cyclopalladated complexes. All the complexes are characterized by means of elemental analysis and i.r. and ¹H n.m.r. spectroscopy. The inversion of the six-membered chelate ring in these complexes is discussed on the basis of temperature-dependent ¹H n.m.r. spectra.