Diverse structures, weak interactions, and catalytic properties of three palladium 2-sulfobenzoate complexes with 1,10-phenanthroline

Abstract

Three complexes with same components, Pd^II, 2-sulfobenzoate and 1,10-phenanthroline, [Pd(phen)₂]⋅2(2-Hsb) (1), [Pd(phen)₂](2-Hsb)⋅(2-Hsb)⋅2H₂O (2), and [Pd(phen)₂]⋅[Pd(phen)(2-sb)₂]⋅6H₂O (3), where 2-H₂sb is 2-sulfobenzoic acid and phen is 1,10-phenanthroline, were synthesized and characterized by IR spectra, elemental analyses, thermogravimetric analyses, UV–vis absorption spectra and powder X-ray analysis. Single X-ray crystal structural analyses showed that 1 and 2 are ionic species, while 3 is a dimer through weak bonding interactions. In 1 and 2, 2-Hsb⁻ ligands are partly deprotonated and it is fully deprotonated in 3. In 2 and 3 there are hydrogen bonds and π–π interactions. Extended hydrogen bonding structures for 2 and 3 are 1-D and 3-D architectures, respectively. The oxidation of methyl phenyl sulfide by 1-3 as homogeneous catalysts gave high conversion and selectivity in methanol. The addition of 2-sulfobenzoic acid in the catalytic reaction further promotes the conversion.

Graphical Abstract

Keywords:

• Palladium complex
• 2-Sulfobenzoate
• Diverse structure
• Catalytic activity