Palladium(II) and Platinum(II) Complexes Bearing ONS-Type Pincer Ligands: Synthesis, Characterization and Catalytic Investigations

TL;DR

This paper reports the synthesis and characterization of new palladium and platinum complexes with ONS-type pincer ligands and their catalytic activity in cross-coupling reactions.

Contribution

The study introduces new Pd(II) and Pt(II) complexes with ONS-type pincer ligands and evaluates their catalytic performance in Suzuki–Miyaura reactions.

Findings

Eight new Pd(II) and Pt(II) complexes were synthesized and characterized using various analytical techniques.

The complexes exhibit square planar geometry with ONS-type pincer ligands and chloride as ligands.

Complexes 3 and 5 showed catalytic activity in Suzuki–Miyaura reactions with yields between 50 and 90%.

Abstract

This work describes the synthesis of eight new Pd(II) and Pt(II) complexes with the general formula [M(TSC)Cl], where TSC represents the 4N-monosubstituted thiosemicarbazone derived from 2-acetylpyridine N-oxide with the substituents CH3 (H4MLO), C2H5 (H4ELO), phenyl (H4PLO) and (CH3)2 (H4DMLO). These complexes have been characterized by elemental analysis, molar conductivity, IR spectroscopy, 1H, 13C, 195Pt and ESI-MS. The complexes exhibit a square planar geometry around the metallic center coordinated by a thiosemicarbazone molecule acting as a donor ONS-type pincer ligand and by a chloride, as confirmed by the molecular structures of the complexes, [Pd(4ELO)Cl] (3) and [Pd(4PLO)Cl] (5), determined by single-crystal X-ray diffraction. The 195Pt NMR spectra of the complexes of formulae [Pt(4PLO)Cl] (6) and [Pt(4DMLO)Cl] (8) in DMSO show a single signal at −2420.4 ppm, confirming the absence of solvolysis products. Complexes 3 and 5 have been tested as catalysts in the Suzuki–Miyaura cross-coupling reactions of aryl bromides with phenylboronic acid, with yields of between 50 and 90%

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