# 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.

## Key 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%