Synthesis and theoretical analysis of palladium complexes of polydimethylsiloxane functionalised pyridine and their catalytic activity in alcohol oxidations under low polar conditions

Palladium(II) complexes of polydimethylsiloxane (PDMS)-functionalised pyridine (1), [Pd(OAc)2(1)2] (2) and [PdCl2(1)2] (3), were synthesised and characterised. The cis/trans isomerism of models of complex 3 was investigated using DFT calculations. Models of complex 2 were also theoretically analysed, to identify any possible C–H⋯O interactions. Complex 2 was investigated as a catalyst for selective alcohol oxidations both under solventless conditions and in supercritical carbon dioxide (scCO2). In scCO2 the presence of 1 was found to stabilise the palladium complex, inhibiting its decomposition to Pd(0), a stabilisation not witnessed with non-PDMS functionalised pyridine analogues.

Graphical abstractPalladium(II) complexes of polydimethylsiloxane functionalised pyridine showed enhanced solubilities in low polar media, facilitating study of the homogeneous, catalytic oxidation of alcohols by molecular oxygen under solventless conditions and in supercritical carbon dioxide.Figure optionsDownload full-size imageDownload as PowerPoint slide