8-CO-ORDINATION IN MANGANESE(II) AND IRON(II) COMPLEXES WITH A PYRAZOLE-FUNCTIONALIZED TETRAAZAMACROCYCLE

The potentially octadentate ligand 1,4,7,10-tetrakis(pyrazol-1-ylmethyl)-1,4,7,10 tetraazacyclododecane (L) gives with manganese(II) the complex [MnL][PF6]2.(CH3)2CO and with iron(II) species of formula [FeLxL'1-x] [PF6]2.solvent where the ligand L' originates from L by substitution of an ethoxy group for a pyrazolyl group in one of the pendant arms of the macrocycle. The crystal structure of [MnL]-[PF6]2.(CH3)2CO has been determined by X-ray diffraction: orthorhombic, space group Pcab, with a 15.801 (6), b = 1 7.973(4), c = 26.793(3) angstrom and Z = 8. The manganese(II) atom is co-ordinated by the eight nitrogen atoms of the L ligand. X-Ray analyses on the isomorphous crystals of the iron(II) species have shown that these contain both eight- and seven-co-ordinate iron(II) in complex cations respectively formed by the L and L' ligands.