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.

Graphical abstract1-(Phenylselenomethyl)-1H-benzotriazole (L1), 1-(4-methoxy phenyltelluromethyl)-1H-benzotriazole (L2), [PdCl2L] and [Ru(η6-p-cymene)(L)Cl](PF6) (L = L1 or L2) have been synthesized. Proton, carbon-13, Se-77 and/or Te-125 NMR spectra authenticate both ligands and their complexes. The single crystal structure of L1, L2, and [Ru(η6-p-cymene)(L)Cl][PF6] (L = L1 or L2) 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 have been explored for Heck and Suzuki C–C coupling reactions (TON upto 9.5 × 104) and Ru-complexes for catalytic oxidation of alcohols (TON ∼ 7.8–9.4 × 104). The Ru-complexes of telluroether ligands are better for catalytic oxidation than those of selenoether ones.Figure optionsDownload full-size imageDownload as PowerPoint slide