SYNTHESES AND CHARACTERIZATION OF MONONUCLEAR AND DINUCLEAR IRON(III)COMPLEXES OF 1,4,7-TRIAZACYCLONONANE-N-ACETATE-(L) - CRYSTAL-STRUCTURES OF [FECL(2)L] AND )CME)L(2)]CLO4-CENTER-DOT-NACLO4-CENTER-DOT-2H(2)O

The macrocycle 1,4,7-triazacyclononane-N-acetate (L) reacted with FeCl 3 . 6H(2)O in water to form the monomeric complex [FeCl(2)L] 1. Hydrol ysis of 1 in the presence of an excess of sodium acetate and sodium pe rchlorate yielded the binuclear complex [Fe-2(mu-O)(mu-O(2)CMe)L(2)]Cl O4 . NaClO4 . 2H(2)O 2. Complexes 1 and 2 have been characterised by X -ray crystallography. In 1 the Fe-III is surrounded by a distorted-oct ahedral array of one fac-co-ordinated triamine ring, one monodentate c arboxylato group and two chloride ligands. Complex 2 consists of a mu- oxo-mu-acetato-diiron(III) core with the distorted octahedral co-ordin ation sphere about each Fe-III being completed by the ligand L. A sodi um ion, with distorted trigonal-bipyramidal stereochemistry, bridges b etween the coordinating carboxylate oxygens of the terminal ligands. C omplex 2 exhibits spectroscopic features and magnetic properties simil ar to those of other mu-oxo-diiron(III) complexes as well as metallopr oteins incorporating a mu-oxo-diiron(III) unit at their active sites.