METAL-ION SELECTIVITY BY MACROCYCLIC LIGANDS .3. THE INTERACTION OF MNII AND COII WITH PYRIDINYL-DERIVED N3O2 MACROCYCLES - X-RAY STRUCTURES OF ENDOMACROCYCLIC COMPLEXES OF MNII AND COII

The interaction of Mn(II) and Co(II) with the macrocycles L1 and L2, each containing an N3O2-donor set, has been investigated. Conductometric titration of the 1:1 Mn(II) complexes with chloride indicated the formation of a 2:1 complex presumably through bridging of a chloride ion. The stability constants of the complexes have been determined in 95% methanol. The X-ray crystal structures of the 1:1 complexes [MnL1Br(EtOH)]ClO4 and [CoL1(NO3)]NO3, have been determined. The metal in [MnL1Br(EtOH)]ClO4 is seven-co-ordinate and lies within the macrocyclic cavity. The donor set comprises the five macrocyclic donor atoms, a bromide anion and an ethanol molecule. Overall, the co-ordination sphere corresponds to a distorted pentagonal-bipyramidal arrangement. The complex [CoL1(NO3)]NO3 also has all donors of the macrocycle co-ordinated together with a nitrate anion. The cobalt is seven-co-ordinated and the co-ordination polyhedron is intermediate between a capped trigonal prism and a pentagonal bipyramid.