Self-assembly of three hetero- and homopolynuclear cyanide bridged complexes of FeII–CuI and CuI: hydrothermal syntheses, structural characterization and properties

Reaction of CuII, K3 [Fe(CN)6] and bidentate diimine ligands by hydrothermal synthesis under different conditions affords one novel heteronuclear FeII–CuI complex, View the MathML source{[Fe2II(bipy)4(μ-CN)4Cu2I(CN)2]·H2O}n(1) (bipy = 2,2′-bipyridine), and two homonuclear CuI complexes, [CuI(μ-CN)(bipy)]n (2) and View the MathML source[Cu3I(μ-CN)3(phen)3]n (3) (phen = 1,10-phenanthroline). Although all the three complexes are 1D cyanide bridged helical chains, they have different helicoids of pseudo-square, pseudo-trigonal and head-to-head bistrigonal for 1, 2 and 3, respectively. The structure of 1 is extended to 2D hexagonal meshed layers by the hydrogen bonding between terminal cyanides and lattice water molecules, which also contain π–π interactions between adjacent sheets. CuI ions in 1 are distorted trigonal planar coordinated by two bridging cyanides and one terminal cyanide, whereas that in 2 and 3 are pseudo-tetrahedral coordinated by two bridging cyanides and two N atoms of a diimine. Both the latter homometallic polymers exhibit similar chain structure, and these chains are close packed with their six adjacent chains in a parallel fashion along the c-axis to form a honeycomb network. It should be noted that complex 1 is the first cyanide bridged FeII–CuI complex of helical chain structure. The spectroscopic properties of complexes 1–3 have also been investigated.