Conformational studies on complexes of a diimine containing a (CH2)2 spacer: crystal structures of a double-stranded Zn(II) meso-helicate and an enantiopure Δ-Cu(II) monohelicate

Ni(II), Cu(II), Zn(II) and Cd(II) complexes of an N4-donor Schiff base, containing (CH2)2 as spacer, have been prepared. The X-ray crystal structures of monohelical Ni(ETs) · H2O and the homochirally crystallised Δ-Cu(ETs), as well as the meso-helicate Zn2(ETs)2 · MeCN [H2ETs: N,N′-bis(2-tosylaminobenzylidene)-1,2-diaminoethane] have been solved. In the latter, the ligand behaves as bis-bidentate, displaying a “C”-type arrangement, instead of the typical “S”-type fashion present in bis-helical dinuclear complexes.