Palladium and half sandwich ruthenium(II) complexes of selenated and tellurated benzotriazoles: Synthesis, structural aspects and catalytic applications

1-(Phenylselenomethyl)-1H-benzotriazole (L1) and 1-(4-methoxyphenyltelluromethyl)-1H-benzotriazole (L2) have been synthesized by reacting 1-(chloromethyl)-1H-benzotriazole with in situ generated nucleophiles PhSe− and ArTe−, respectively. The complexes of L1 and L2 with Pd(II) and Ru(II)(η6-p-cymene) have been synthesized. Proton, carbon-13, Se-77 and/or Te-125 NMR spectra authenticate both the ligands and their complexes. The single crystal structures of L1, L2 and [RuCl(η6-p-cymene)(L)][PF6] (L = L1: 3, L = L2: 4) have been solved. The Ru–Se and Ru–Te bond lengths have been found 2.4801(11) and 2.6183(10) Å, respectively. The palladium complexes, [PdCl2(L)] (L = L1: 1, L = L2: 2) have been explored for Heck and Suzuki–Miyaura C–C coupling reactions. The TON values are upto 95,000. The Ru-complexes have been found promising for catalytic oxidation of alcohols (TON ∼ 7.8–9.4 × 104). The complexes of telluroether ligands are as efficient catalysts as those of selenoether ones and in fact better for catalytic oxidation.