Metallation of Aliphatic Carbon Atoms. IV. Syntheses and Characterization of the Cyclopalladated Complexes of 2-t-Butylbenzothiazole

Article abstract of DOI:10.1246/bcsj.59.3073

2-t-Butylbenzothiazole reacts with palladium(II) acetate in acetic acid to produce the cyclopalladated dimer <(Pd(CH2CMe2-C7H4NS)(μ-MeCO2))2> (2) (C7H4NS=2-benzothiazolyl).Complex 2 shows temperature-dependent 1H NMR spectra, which have been interpreted on the basis of the inversion motion of the acetato bridges.Metathesis of 2 with lithium chloride and sodium iodide result in the formation of the chloro- and iodo-bridged analogues, <(Pd(CH2CMe2-C7H4NS)(μ-Cl))2> (3) and <(Pd(CH2CMe2-C7H4NS)(μ-I))2>(4), respectively, each of which is found to be composed of cis and trans isomers.The 1H NMR spectra of 3 and 4 depend on temperature and are ascribed to rapid exchange between the two isomers.Equimolar amounts of 3 and 4 afford a μ-chloro-μ-iodo binuclear complex, <(C7H4NS-CMe2CH2)Pd(μ-Cl)(μ-I)Pd(CH2CMe2-C7H4NS)>.The reaction of 3 with thallium(I) acetylacetonate produces a mononuclear cyclopalladated complex .Complexes 2 and 3 react with CO in methanol to give MeO2CCH2CMe2-C7H4NS, the formation of which comfirms also the cyclopalladated structure of 2-t-butylbenzothiazole in 2 and 3.