SYNTHESIS AND CHARACTERIZATION OF (4S)-1-CHLOROALKYLSILATRANE-4-CARBOXYLIC ACIDS CRYSTAL-STRUCTURES OF ,4S)-1-CHLOROMETHYL-3-METHYLSILATRANE-4-CARBOXYLIC ACID AND -1-(3-CHLOROPROPYL)-3-METHYLSILATRANE-4-CARBOXYLIC ACID

(4S)-1-(chloromethyl)silatrane-4-carboxylic acid 1 and ,4S)-1-chlorome thyl-3-methylsilatrane-4-carboxylic acid 2 were synthesized by the tra nsesterification of chloromethyltriethoxysilane with L-N,N-bis(2-hydro xyethyl)serine or L-N,N-bis(2-hydroxyethyl)threonine in the presence o f pyridine. (4S)-1-(3-chloropropyl)silatrane-4-carboxylic acid 3 and - 1-(3-chloropropyl)-3-methylsilatrane-4-carboxylic acid 4 were similarl y synthesized from the reaction of 3-chloropropyltrimethoxysilane with the chiral ligands. The compounds were characterized by elemental ana lyses, IR spectra, H-1 and C-13 NMR spectra and mass spectra. The stru ctures of compounds 2 and 4 were determined by X-ray single crystal di ffraction. It is shown that the silatranyl carboxylic acids are linked by the intermolecular hydrogen bonds to give linear polymer in the cr ystals, and the equatorial Si-O oxygens behave as proton accepters. It seems that the influence of the carboxylic group on the Si-N dative b ond of compound 4 is greater than that of compound 2.