Binaphthyl Schiff base complexes of palladium(II). Structures and reactivities toward alkene epoxidation
- 9 March 2000
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 7,p. 1075-1080
- https://doi.org/10.1039/a908917i
Abstract
Palladium(II) binaphthyl Schiff base complexes [PdII(L)] (1: H2L = (racemic or R)-2,2′-bis(3,5-dichloro-2-hydroxybenzylideneamino)-1,1′-binaphthyl (H2L2); 2: H2L = (R)-2,2′-bis(3,5-dichloro-2-hydroxylbenzylideneamino)-5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-binaphthyl (H2L3)) were prepared from sequential reactions of H2L with sodium methoxide and palladium(II) acetate in methanol in about 70% yields. Both complexes 1 and 2 have been characterised by X-ray crystallography as well as 1H NMR, IR, UV/VIS and MS spectroscopy. The structures of 1 and 2 feature a pseudo planar N2O2 arrangement with the Schiff base ligands adopting a stepped conformation, in contrast to the non-planar N2O2 geometry usually observed for this type of Schiff base bound to various metal ions. The catalytic behaviour of complexes 1 and 2 toward asymmetric epoxidation of styrenes was investigated. With 2 as a catalyst, a 71% ee was obtained for the epoxidation of p-fluorostyrene by tBuOOH.Keywords
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