MACROCYCLIC METAL-COMPLEXES .22. DINUCLEAR MACROCYCLIC FLUOROBOROBRIDGED COMPLEXES OF COBALT(II) AND NICKEL(II)

Dinuclear fluoroboro-bridged macrocyclic complexes have been synthesised by treating boron trifluoride on bis-(diacetylazinedihydrazone)dinickel(II)/dicobalt(II) complexes. The complexes possess the stoichiometry [M2(DAADHBF2)2X4] (BF4)2 {M = Co(II), X = Cl-, Br-, I-, SCN-; M = Ni(II), X = SCN-}. They are ionic in nature and the IR spectral data show the existence of fluoroboro groups as > BF2+ and BF4- species. Pairs of former group occur as bridgeheads, each encompassing two adjacent NH2 groups in the inner-sphere of the macrocyclic ligand frame and the tatter occupies the outer coordination sphere of the complex. Polararographic redox studies show three single-electron redox steps and the thermodynamic parameters, viz. E1/2(1,2) values point to the macrocyclic structure of the complexes.