NOVEL COORDINATION-COMPOUNDS OF QUINIC ACID - X-RAY-DIFFRACTION STUDYOF COPPER(II) COMPLEXES WHERE THE METAL-ION WAS A CHIRAL CENTER

The synthesis and characterization of the following coordination compo unds derived from quinic acid (quin) (1): [Cu(guin)Cl(H2O)](n).(H2O)(n ) (2); [Ni(quin)Cl(H2O)](n). (2H(2)O)(n) (3); [Co(quin)Cl(H2O)](n).(2H (2)O)(n) (4); [Cu(quin)(NO3)(H2O)](n).(2H(2)O)(n) (5); [Cu(quin)(AcO)( H2O)]n. (2H(2)O)(n) (6); [Cu(quin)H2O](2).2H(2)O (7); [Co(quin)(2)](n) (8); [Zn(quin)(2)] (9); [Cd(quin)(2)](10) and [Hg(quin)(2)]. 4H(2)O ( 11) is presented. All of the compounds were characterized by i.r. and u.v. spectroscopy; in addition, (9) and (10) were analysed by n.m.r., and (2), (5) and (7) by X-ray crystallography. Due to the polyfunction ality of quinic acid diverse structures were obtained: (2)-(6) and (8) were polymeric, (7) was dimeric and (9)-(11) were spiranic. In compou nd (2) the Cu had a distorted octahedral structure; it was a chiral ce ntre with six different substituents and an optically active ligand. O nly one stereoisomer (OC-6-25-Delta) of the 30 possible was observed i n the crystal. Compound (5) was also polymeric, the hexacoordinated Cu atom was a chiral centre (OC-6-53C) and only one stereoisomer was obs erved. It was bonded to three quinic acid ligands in three different c oordination modes and each quinic acid was in turn bonded to three dif ferent Cu atoms. Each chain was linked to another two chains giving a net structure. Compound (7) was a dimer with two square pyramidal Cu a toms. Two apical water molecules were found in a cis arrangement. Each quinic acid ligand was bonded to two Cu atoms which were linked by tw o oxygen bridges and each Cu atom was bonded to two quinic acid moieti es.