Preparation, spectroscopic and magnetic characterization of Cu(cyclam)M(CN)4 complexes exhibiting one-dimensional crystal structures (cyclam=1,4,8,11-tetraazacyclotetradecane, M = Ni, Pd, Pt)

From the systems Cu(II)-cyclam-[M(CN)(4)](2-) (cyclam = 1,4,8,11-tetraazacyclotetradecane; M = Ni, Pd, Pt), three cyanidocomplexes Cu(cyclam)M(CN)(4) [M = Ni (1), Pd (2), Pt (3)] were isolated and characterized by chemical analysis, IR and UV-VIS spectroscopy. The three compounds are isostructural, and their crystal structures are formed by quasi-linear chains exhibiting [-Cu(cyclam)-mu-NC-M(CN)(2)-mu-CN-](n) composition. The Cu(II) atoms reside on centres of symmetry and are coordinated in the form of an elongated octahedron with mean equatorial Cu-N bonds of 2.015(12), 2.017(13) and 2.011(11) in (1), (2) and (3), respectively, and weakly N-bonded bridging cyanido ligands in the axial positions [2.5321(9) in (1), 2.518(2) in (2) and 2.549(3) in (3)]. Hydrogen bonds of the N-H center dot center dot center dot N-cyanido center dot center dot center dot H-N type link neighbouring chains, and a topologically square network of paramagnetic Cu(II) atoms is formed. The magnetic susceptibilities of all three complexes follow the Curie-Weiss law with a weak antiferromagnetic exchange coupling below 5 K.