Synthesis and properties of nickel(II) and copper(II) complexes of a di-N-acetamide tetraaza macrocycle

The syntheses of the hexadentate ligand 2,13-bis(acetamido)-5,16-dimethyl-2 ,6,13,17-tetraazatricyclo[14,4,0(1.18),0(7.12)]docosane (L-2) and its compl exes with Ni(II) and Cu(II) are described. Crystal structures of H2L2. 2HCl O(4) (1), [Ni(L-2)](ClO4)(2) (2) and [Cu(L-2)](ClO4)(2) (3) are reported. T he two pendant acetamide groups of the macrocyclic ligand 1 are trans to ea ch other and the absolute configuration is a trans-IV in the solid state. T he crystal structures of 2 and 3 revealed an axially elongated octahedral g eometry with four nitrogen atoms of the macrocycle and two oxygen atoms of the pendant acetamide groups at the axial positions. The nickel(II) and cop per(II) ions are located at an inversion center. The electronic spectra and electrochemical behaviors of the complexes are significantly affected by t he presence of the pendant arms. (C) 2001 Elsevier Science Ltd. All rights reserved.