MODEL FOR THE REDUCED SCHIFF-BASE INTERMEDIATE BETWEEN AMINO-ACIDS AND PYRIDOXAL - COPPER(II) COMPLEXES OF N-(2-HYDROXBENZYL)AMINO ACIDS WITH NONPOLAR SIDE-CHAINS AND THE CRYSTAL-STRUCTURES OF (2-HYDROXBENZYL)-D,L-ALANINE)(PHEN)]CENTER-DOT-H2O AND [CU(N-(2-HYDROXYBENZYL)-D,L-ALANINE)(IMIDAZOLE)]

Copper(II) complexes with reduced Schiff base ligands of amino acids p ossessing nonpolar side chains with salicylaldehyde have been synthesi zed. Ternary complexes with imidazole, 1,10-phenanthroline, and pyridi ne have been prepared and characterized for N-(2-hydroxybenzyl)-D,L-al anine. The crystal structures of xybenzyl)-D,L-alanine)(1,10-phenanthr oline)Cu(II)] monohydrate ([Cu(SAla)phen]. H2O) and N-(2-hydroxybenzyl )-D,L-alanine)(imidazole)Cu(II)] ([Cu(SAla)Him]), have been determined . [Cu(SAla)phen]. H2O crystallized in space group <P(1)over bar>, with a = 8.718(2) Angstrom, b = 10.886(3) Angstrom, c = 11.693(2) Angstrom , alpha = 71.32(2)degrees, beta = 85.27(2)degrees, gamma = 70.21(2)deg rees, and Z = 2. The copper atom is five coordinate, with SAla acting as a tridentate ONO chelator through the carboxylato and phenolato oxy gens and the amine nitrogen. The remaining donors are provided by the phen nitrogens. [Cu(SAla)Him] crystallized in space group P2(1)/n, wit h a = 10.353(1) Angstrom, b = 6.714(1) Angstrom, c = 18.769(2) Angstro m, beta = 91.71(1)degrees, and Z = 4. The copper atom is four coordina te, with SAla acting as a tridentate ONO chelator with the neutral imi dazole moiety coordinated through nitrogen. In both complexes the liga nd has two chiral centers due to the coordination of the N. Molecular mechanics calculations show that unfavorable steric interactions would occur in the nonobserved R,R and S,S diastereomers. Compounds prepare d have been characterized by a range of physicochemical techniques. Th e complexes may serve as stable models for the intermediates in enzyma tic amino acid transformations.