A new type of chiral pentacoordinated silicon compounds with azomethine ligands made from acetylacetone and amino acids

Azomethines of acetylacetone with amino acids have been utilized to prepare chiral pentacoordinated silicon compounds. The sodium salt of the ligand 6 has been synthesized from acetylacetone and L-phenylalanine in presence of sodium hydroxide. Reaction of 6 with equimolar amounts of dichlorodiorganosilanes in presence of triethylamine gave the chiral silicon complexes 7a–c. These contain a R2SiONO’ skeleton, wherein the pentacoordination is reached by coordination of the acetylacetonate oxygen, the imine nitrogen, and one carboxylate oxygen atom of the azomethine ligand to the SiR2 unit. 7a–c were characterized by elemental analyses, single crystal X-ray diffraction, UV–Vis–spectroscopy, value of optical rotation, and NMR-spectroscopy.