Synthesis and characterization of Ni(II) and Cu(II) complexes of 6-(β-(3,4-dimethoxyphenylethyl))cyclam (L1) and 6-(β-(3,4-dihydroxyphenylethyl))cyclam (H2L2) (cyclam=1,4,8,11-tetraazacyclotetradecane). X-ray crystal structures of [Cu(L1)Br2] and [Cu(H2(BrL2))Br]Br·H2O and metal ion templated formation of multinuclear macrocyclic complexes

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The synthesis of 6-(β-(3,4-dimethoxyphenyl)ethyl)cyclam (L1) and the corresponding Ni(II) and Cu(II) complexes is described. Demethylation of the complexes of L1 was carried out with BBr3 and the corresponding Ni(II) and Cu(II) complexes of H2L2 (H2L2=6-(β-(3,4-dihydroxyphenyl)ethyl)cyclam) have been isolated and characterized. Reaction of [Cu(L1)Br2] with Br2 resulted in bromination of the phenyl group, to yield [Cu(BrL1)Br2]. Demethylation of [Cu(BrL1)Br2] yielded the corresponding bromo-catechol appended macrocyclic complex [Cu(H2(BrL2))]Br2, where H2(BrL2)=6-(β-(6-bromo-3,4-dihydroxyphenyl)ethyl)cyclam. The crystal structures of [Cu(L1)Br2] and [Cu(H2(BrL2))Br]Br·H2O have been determined. In both complexes, the Cu(II) ion is within the macrocyclic cavity with an average Cu-N distance of (2.01 Å). In [Cu(L1)Br2], the Cu(II) is pseudo-octahedral, with Cu-Br(1)=2.9996(3) and Cu- Br(2)=2.925(3) Å whereas in [Cu(H2(BrL2))Br]Br·H2O, the Cu(II) is square pyramidal with a Cu-Br distance of 2.904(2) Å. Reaction of [M(H2L2)]2+ (M=Ni2+ and Cu2+) ions with Fe(III) in basic aqueous media led to the formation of the tetranuclear species [Fe(M(L2)Br2)3]3−, which has been monitored by UV–Vis and EPR spectroscopy.