Copper(ii) cyclam-based complexes for radiopharmaceutical applications: synthesis and structural analysis† †The HTML version of this article has been enhanced with colour images. ‡ ‡Electronic supplementary information (ESI) available: Packing diagrams for the Cu(H2TETA) structures and further details of the compounds used in the structural distortion analysis. See DOI: 10.1039/b615329a Click here for additional data file. Click here for additional data file.

Two molecular structures of the copper(II) complex, Cu(H(2)TETA), have been determined by X-ray crystallography. The Jahn-Teller distortion differs between the two structures; occurring either along the axis of the pendant acetate arms or across the macrocyclic ring. An analysis of deposited data from over one hundred copper(II) cyclam X-ray structures in the Cambridge Structural Database (CSD) reveals that Jahn-Teller distortion across the ring is highly unusual for such compounds in the solid state. Novel chelators based on the piperazino/side-bridged cyclam have been prepared and copper(II) complexes formed. The single crystal X-ray structures of two copper(II) complexes, with either an ester or acid N-pendant arm, have been determined and in both cases the pendant arm is bound to the metal centre.