Non-template synthesis of new tetra-aza macrocyclic ligands and their cobalt, nickel, and copper complexes: X-ray structure of (5,14,15,16,17,18-hexahydro-7-methyldibenzo[b,i][1,4,8,11]tetra-azacyclotetradecinato) nickel(II) monoperchlorate

Abstract

Reaction of the open-chain tetramines 1,3-bis(o-aminophenylamino)propane (L) or 1,3-bis(o-amino-p-methylphenylamino)propane (L′) with 3-ethoxy-2-methylacrolein gives the title macrocycle, HL1, or its methyl substituted derivative, HL2, in yields of the order of 40% without recourse to either high dilution or metal template techniques. Reaction of HL1 or HL2 with CoII, NiII, or CuII salts is accompanied by deprotonation of the ligand and its co-ordination to the metal ion as a monoanionic species. The X-ray structure of [NiL1][ClO4](1) confirms the site of deprotonation and establishes the square planar geometry of the metal ion. Treatment of [NiL1][ClO4] with NEt3 in air results in oxidative dehydrogenation of the ligand and the isolation of [Ni(C19H16N4)]. Crystals of (1) are triclinic, space group P, with a= 12.351(3), b= 10.596(3), c= 7.841(3)Å, α= 91.971(3), β= 92.654(3), γ= 108.978(3)°, and Z= 2.