Synthesis, crystal structure and magnetic properties of the binuclear copper ( 11) complex of a new bis ( 1 , 4 7 10-tetraazacyclododecane) ligand help to elucidate the factors that determine the electronic and magnetic pruperties in the polynuclear bio-site.
The ligands that comprise two macmycles, such as 1 , 4,7-triazacyclonane , 1 , 5 ,9-triazacyclododecane, and 1,4,7,I@tetraaurcyclododecane (cyclen) moieties have enabled the formation of a variety of binuclear complexes containing metal ions such as Mn( WIII) , Fe ( WIII) , Co(WIII), Cu( II), and Zn( 11) .4 These ligands tethered by various bridging groups, such as polymethylene, methylphenol and py-ramle,'*4 provide an excellent motif to study the variations of chemical properties of binuclear complexes as changes are introduced into the ligand frameworks. 'Ihe change of the bridpg p u p s linking the binuclear metal centers might adjust the distance between metal centers in binuclear complexes and the &tive properties.' Macrocycles linked via polpthylene bridges and their complexes have been reported, 1.2*4 but the ligands that contain two macmycles bridged by phenyl groups are relative r a t . We report herein the synthesis , crystal structure and magnetic prupeities of the binuclear copper (II) complex of a new bis(macr0Cyclic) ligand comprising two 1,4,7,1O-tetmamcyclododme (cyclen) subunits bridged by 2, 6-bimethybthoqbenzene ( Chart 1 ) . Keyword antifemmagnetic ooupling, binucleating macrocyclic ligand Binuclear copper ( 11) complex, crystal structure,
The synthesis and complexation prupdes of ligands comprising linked macrocycles have attracted considerable attention in recent years.'J Such ligands can form binuclear complexes and can be used in modeling studies for impomt biological molecules such as metalloproteins. simplified model complexes of this type may