Three-ring, branched cyclam derivatives and their interaction with nickelii, copperii, zincii and cadmiumiiElectronic supplementary information (ESI) available: Fig. 1S: Spectrophotometric titration curve for the addition of nickel(ii) nitrate hexahydrate to 3. Fig. 2S: EPR spectra for the copper(ii) perchlorate complexes of (a) 1, (b) 2and (c) 4. Fig. 3S: EPR spectrum for the copper(ii) perchlorate complex of 3. Figs 4S–6S: Cyclic voltammograms for [Ni(2)](ClO4)2, [Ni3(3)](ClO4)6and [Ni3(4)](ClO4)6. See http://www.rsc.org/suppdata/dt/b4/b401254m/

The interaction of two symmetrically branched tris-cyclam derivatives based on 1,3,5-trimethylenebenzene and phloroglucinol cores with nickelii, copperii, zincii and cadmiumii is reported. All four metal ions yield solid complexes in which the metal ligand ratio is 3 1. For both ligand types, spectrophotometric titrations confirm the formation of nickelii and copperii complexes of similar 3 1 stoichiometry in dimethyl sulfoxide. Visible spectral, electrochemical, magnetic moment, ESR and NMR studies have been performed to probe the nature of the respective complexes. Where appropriate, the results from the above metal-ion studies are compared with those from parallel investigations in which the corresponding substituted mono-cyclam analogues were employed as the ligands. A structural determination employing a poorly diffracting crystal of the trinuclear nickelii complex of the tris-cyclam ligand incorporating a 1,3,5-trimethylenebenzene core was successfully carried out with the aid of a synchrotron radiation source. A nickel ion occupies each cyclam ring in a square-planar coordination arrangement, with each cyclam ring adopting the stable trans-III configuration.