Synthesis, structures, and magnetic properties of one-dimensional Fe–M (M = NiII, CuII) coordination polymers bridged by nitroprusside

Self-assembling [Fe(CN)5(NO)]2− and [M(L)]2+ (M = Ni, Cu; L = macrocycles) led to one-dimensional coordination polymers, [Ni(L1)][Fe(CN)5(NO)] · 2H2O (1) with parallel chains and [Cu(L2)][Fe(CN)5(NO)] · 3H2O (2) exhibiting a slanted chain structure. Compound 1 contains a planar macrocycle L1 coordinated to a slightly distorted octahedral Ni(II) ion in which the planarity of L1 gives rise to piling up chains in parallel. In contrast, a more flexible macrocyclic ligand L2 in 2 that surrounds a Cu center with a tetragonal elongation has bulky cyclohexyl groups together with pendant methyl side groups. The presence of the methyl groups on L2 in a chain makes the cyclohexyl groups in an adjacent chain tilted against the CuN4 basal plane with the methyl groups, eventually resulting in the slanted chain structure. Magnetic data demonstrate that antiferromagnetic interactions (J ≈ −0.13 cm−1) are operating although the paramagnetic centers are linked by the long diamagnetic [Fe(CN)5(NO)]2− anion.