Macrocyclic metal complexes: Part XXII-Dinuclear macro cyclic fluoroborobridged complexes of cobalt(II) and nickel(II)

Abstract

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 > BF and BF species. Pairs of former group occur as bridgeheads, each encompassing two adjacent NH₂groups in the inner-sphere of the macrocyclic ligand frame and the latter occupies the outer coordination sphere of the complex. Polarographic redox studies show three single-electron redox steps and the thermodynamic parameters, viz. <i>E </i>_1/2^1.2, values point to the macrocyclic structure of the complexes.