Synthesis and characterization of a novel quinoxaline-substituted vic-dioxime and its complexes containing bis(12-diazacrown-4) derivatives

A new quinoxaline-substituted vicinal dioxime ligand containing bis(12-diazacrown-4) units (H2L) was synthesized by the reaction of cyanogen di-N-oxide with compound 4. Mononuclear Ni-II and Cull complexes with a metal: ligand ratio of 1:2 for HA and a trinuclear Cull complex were also synthesized. The mononuclear Cull species coordinated to two Cull ions through the deprotonated oximate oxygens to yield a trinuclear structure cis-bridged by the oximate groups, with 1, 1 0-phenanthroline as an end-cap ligand. The mononuclear Co-III complex of HA was isolated with pyridine and chlorine as axial ligands. In addition, a Co-III complex containing the BF2+ bridge macrocycle was synthesized using a precursor hydrogen-bridged Co-III complex via a template effect. The extraction abilities of 1, 3, and 11 were also evaluated in 1,2-dichloroethane by using several alkali (Li+, Na+, K+, and Cs+) and tran sition -metal picrates, such as Ag+, Pb2+, Cd2+, Cu2+, and Zn2+, Structures of the ligands and metal complexes were solved by elemental analyses, H-1 and (CNMR)-C-13, FT-IR, UV-vis, and mass spectra.