Influence of ligand backbones and counter ions on structures of helical silver(I) complexes with di-Schiff bases derived from phthalaldehydes and diamine

Five silver(I) complexes of Schiff bases, [Ag2L2][ClO4](2) 1, [Ag2L2][PF6]( 2).H2O 2, [Ag2L2][NO3](2) 3, (1)(infinity)[(AgL')(dnb)(H2O)(0.25)] (dnb=3,5 -dinitrobenzoate) 4 and (1)(infinity)[(AgL')(NO3)] 5 were synthesized, wher e L and L' are derived from the [1+2] condensation of 2-(aminoethylamino)et hanol with isophthalaldehyde or terephthalaldehyde. Complexes 1, 2, 4 and 5 have been structurally characterised by X-ray crystallography, which shows that the cations in 1 and 2 have similar double helical structures, and 4 has a single-stranded helical structure. However, complex 5 exhibits a one- dimensional staircase-like structure. Each Ag atom in 1, 2 and 4 adopts a h ighly distorted tetrahedral geometry, while that in 5 features a T-shaped g eometry. In solution, 1-3 have virtually identical H-1 NMR spectra, similar FAB mass spectra and electrochemical properties.