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Preparations and Properties of Some Gationic Palladium(II) Complexes of the Di- t -butylnitroxide Radical

1977; Oxford University Press; Volume: 50; Issue: 5 Linguagem: Inglês

10.1246/bcsj.50.1070

1348-0634

Masaaki Okunaka, Gen‐etsu Matsubayashi, Toshio Tanaka,

Metal-Catalyzed Oxygenation Mechanisms

Abstract Cationic palladium(II) complexes of the di-t-butylnitroxide radical, [Pd(But2NO)(L-L)]X (L-L=2,2′-bipyridine, 1,10-phenanthroline, N-substituted 2-pyridylmethyleneamine and bis(triphenylphosphine); X−=ClO4-and/or BPh4−), were prepared. 1H NMR spectra of the complexes indicate that the nitroxide forms a three membered ring with the palladium atom. The N-methyl- and N-ethyl-2-pyridylmethyleneamine complexes exist as two geometrical isomers in solution, whose ratios are 1 : 1 and 1 : 0.2, respectively. In the N-butyl and N-p-tolyl analogs, however, only one of the isomers exists in solution. These results are interpreted in terms of steric repulsion between the t-butyl groups and N-substituents. The bipyridine complex reacts with dialkyl disulfides in the presence of catalytic amounts of bipyridine to give a sulfur-bridged dimeric complex, [Pd(bipyridine)(SR)]2(ClO4)2(R=Me and Pr), and a free nitroxide radical.