CRYSTAL-STRUCTURES OF COPPER(II) COMPLEXES OF SOME 2-METHYL-8-QUINOLINOLS AND IMPLICATIONS FOR THEIR ANTIFUNGAL ACTIVITY

A hypothesis that the geometry of a potential fungicide must be consis tent with that of the pores of the fungal spore wall in order to penet rate it and be toxic has been developed. Certain bis(8-quinolinolato)c opper(II) complexes seemed to contradict this. To resolve this issue, structures of bis(7-fluoro-8-quinolinolato)copper(II) (1), bis(2-methy l-8-quinolinolato)copper(II) (2), and bis(2-methyl-7-nitro-8-quinolino lato)copper(II) (3) were solved. The ligands of 1 are square planar wi th copper at the center of symmetry. In 2 and 3 the methyl group at C2 interacts with the other 8-quinolinol ligand, producing a significant distortion of the square planar geometry which causes a rotation abou t the N-Cu-N axis and allows the molecules to be polar, more compact, and manifest their toxicity. Bis(7-Nitro-8-quinolinolato)copper(II) is square planar and nontoxic.