Metal-metalloid bond containing complexes of the bulky organotellurium ligand: applications in catalysis of C–O coupling and aldehyde to amide transformation reactions

Abstract

Anthracene-based ligand L1 comprising an imine functionality and a tellurium (Te) donor moiety has been prepared. This ligand L1 has been characterized using ¹H, ¹³C and ¹²⁵Te NMR spectroscopic techniques. The novel palladium(II) complex 1 and ruthenium(II) complex 2 have been synthesized by reacting organotellurium ligand L1 and Na₂PdCl₄/[Ru p(cymene)Cl₂]₂, respectively. The Pd(II) complex 1 and Ru(II) complex 2 were characterized with high resolution mass spectrometry (HR-MS) and ¹²⁵Te NMR spectra. The molecular structures of complexes 1 and 2 were authenticated with single crystal X-ray diffraction. Both the complexes are thermally stable, robust, and air and moisture insensitive. Palladium complex 1 exhibits nearly square planar geometry. The molecular structure of complex 2 has a pseudo-octahedral half sandwich piano-stool geometry around ruthenium. The catalytic activity of complex 1 has been explored for O-arylation of phenol, whereas the catalytic activity of complex 2 was explored for aldehyde to amide conversion. A variety of structurally different chloroarenes have been coupled with phenol employing 1 as a catalyst. A wide range of aldehydes containing different functional groups (viz. H, –Me, –NO₂, F, OMe, Cl and Br at the para position) were readily converted into their corresponding amide by employing Ru(II) complex 2 as a catalyst in a reaction time of 12 hours.