Transition-metal complexes of the macrocyclic ligand 5,12-dimethyl-1,4,8,11-tetra-azacyclotetradeca-4,11-diene

Abstract

The macrocyclic ligand 5,12-dimethyl-1,4,8,11-tetra-azacyclotetradeca-4,11-diene (L¹) has been prepared as its dihydroperchlorate salt by the reaction of ethane-1,2-diamine monohydroperchlorate with methyl vinyl ketone. A transoid arrangement of the imine linkages has been confirmed by a crystallographic study on trans-[CoL¹(SCN)₂]-SCN·H₂O. A number of metal(II) complexes [ML¹][ClO₄]₂(M = Ni, Cu, Co, or Zn) have been prepared. In addition a series of octahedral cobalt(III) complexes of the general type trans-[CoL¹X]ⁿ⁺(X = Cl^–, Br^–, NO₂^–, SCN^–, or NH₃) and cis-[CoL¹(aa)]ⁿ⁺(aa = CO₃^2– or acac^–) have been synthesised. Two separate isomers of trans-[CoL¹Cl₂][ClO₄]₂ have been identified corresponding to the rac- and meso-diastereoisomers resulting from the asymmetric secondary nitrogen donors. The co-ordination chemistry of L¹ is discussed and i.r. and d–d electronic spectra are reported.