Dicopper cryptates with 1,1 and 1,3 bridging ligands: spectroscopic, magnetic and electrochemical properties

The furan-based hexaiminocryptand L1, N[(CH2)2NCHRCHN(CH2)2]3N where R = furan-2,5-diyl, has been found to act as host for dicopper(I) and µ-hydroxo-dicopper (II). The corresponding octaaminocryptand derivative L2 accommmodated dicopper(II) with hydroxide, imidazolate or azide bridging ligands. A single-crystal X-ray analysis of [Cu2L1][BF4]2 revealed trigonal-pyramidal co-ordination for CuI together with a Cu ⋯ Cu separation of 4.2 Å. The µ hydroxo-dicopper(II) cryptate [Cu2L2(OH)][CF3SO3]2 was found to have trigonal-bipyramidal geometry, with a Cu ⋯ Cu separation of 3.9 Å and the Cu–OH–Cu assembly close to linear. Effective magnetic exchange arising from collinear disposition of bridge O 2p, and copper(II) magnetic orbitals makes the hydroxo-bridged derivatives effectively diamagnetic.