ZINC-COMPLEXES OF CYCLOHEXANE TRIAMINE LIGANDS

The synthesis and characterization of zinc complexes of the cis-cyclohexane triamine derived ligands C6H9(NH2)3 (L1), C6H9(NHMe)3 (L2) and C6H9(N = CHPh)3 (V) are described. L1 forms 1:1 complexes with ZnCl2, ZnBr2, ZnI2 and Zn(OAc)2, and 2:1 complexes with Zn(ClO4)2 and Zn(CF3SO3)2. For L2, no 2:1 complexes with zinc salts could be obtained, but 1:1 complexes with ZnCl2 and Zn(NO3)2 were obtained. V was hydrolyzed in the presence of zinc salts. Physical properties and spectra indicate that the complexes of ZnHal2 and Zn(NO3)2 contain tetrahedral LZnX cations and free X anions, while L1Zn(OAc)2.H2O seems to consist of octahedral molecular units containing monodentate acetate ligands. According to NMR, the 2:1 complexes (L1)2Zn(CF3SO3)2 and (L1)2Zn(ClO4)2 are octahedrally coordinated while (L1H)2Zn(ClO4)4 contains tetrahedral zinc with only bidentate L1 ligands. A crystal structure determination has proved the octahedral geometry of (L1)2Zn(CF3SO3)2. NMR studies have shown that there is no or little ligand exchange of the complexes in solution.