Synthesis of a novel six membered CNS palladacycle; TD-DFT study and catalytic activity towards microwave-assisted selective oxidation of terminal olefin to aldehyde

• The complex formed is a new six membered palladacycle, having slightly distorted square planar geometry.
• The electronic absorption spectrum of the complex was calculated using the TD-DFT method in the Gaussian 09W programs.
• Pd(II) complex catalyzed selective oxidation of terminal alkenes to aldehyde by a microwave assisted Wacker method.
• The reaction is efficient in terms non-hazardous solvent selection, high yield and selective conversion almost up to 99%.

This article documented synthesis of a Schiff base, E-2-(benzylthio)-N-{(2-methoxynaphthalene-1-yl)methylene}benzenamine (HL) by the treatment of 2-meyhoxynaphthaldehyde and 2-(benzylthio)aniline. Reaction of this synthesized Schiff base with Na2PdCl4 has been investigated, which gave a novel six membered Pd(II) complex (PdLCl) through C,N,S-donor atom of Schiff base. These two newly synthesized compounds were characterized by 1H NMR, FTIR and UV–Vis spectra and structure of the Pd(II) complex was confirmed by X-ray crystallography. The catalyst (PdLCl) displayed considerable reactivity (up to 99% selectivity and 90% yield) in the selective oxidation of terminal CC bond in aryl substituted olefin to aldehyde. The method shows good functional groups compatibility, no ketone byproducts and is operationally simple. Time dependent density functional study (TD-DFT) of representative cyclopalladated complex has been undertaken. The simulated optical spectrum of the complex is in good agreement with the experimentally observed spectrum.

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