COMPLEXES WITH MACROCYCLIC LIGANDS .3. MONONUCLEAR AND DINUCLEAR MACROCYCLIC TRANSITION-METAL COMPLEXES OF LIGANDS OF SCHIFF-BASE TYPE - SYNTHESES, STRUCTURES, ELECTROCHEMICAL AND MAGNETOCHEMICAL PROPERTIES

Four new mononuclear metal(II) complexes (4a-d) of a macrocyclic ligand derived from the Schiff base condensation of 2 equiv. of 1,2-phenylenediamine (3a) and 5-tert-butyl-2-hydroxy-1,3-benzenedicarbaldehyde (2) were synthesized and the cobalt complex 4b characterized by X-ray structure analysis. Reaction of 1,2-diamino-3,4,5,6-tetrafluorobenzene (3b) with the dicarbaldehyde 2 in the presence of Mn(ClO4)2 or Co(ClO4)2 leads to the novel metal-free macrocyce 6 (X-ray structure determination). The macrocycle 6 and Cu(ClO4)2 yield the new dinuclear copper complex 8, the structure of which was also determined by X-ray diffraction. The copper-(II) ions in 8 have a distorted square-pyramidal coordination by the four donor atoms of the macrocycle and an apical acetonitrile ligand. The Cu...Cu distance is 318.1 pm, and the two Cu(II) ions show only a small antiferromagnetic exchange interaction of J = -41 cm-1. Another new dinuclear Cu(II) complex (10) of a macrocyclic ligand derived from the Schiff base condensation of 2,2'-diaminooctafluorobiphenyl (9) and dicarbaldehyde 2 was synthesized and characterized by X-ray structure analysis, electrochemical investigations (DCV), and variable-temperature magnetic susceptibility measurements. One copper ion in complex 10 is five-coordinate (square-pyramidal), the other one six-coordinate (distorted octahedral). The Cu...Cu distance is 301.5 pm and the antiferromagnetic coupling J = -774 cm-1.