Cyanide bridged 2-D homometallic mixed-valence copper coordination polymer: synthesis, crystal architecture, Hirshfeld surface analysis and magnetic behavior

A 2-D homometallic mixed-valence copper coordination polymer, catena-poly[[tetrakis(mu-cyanido)-{(1-(N-acetopyridinine)-2-aminoethane)}-tri-copper] methanol monosolvate], {[Cu-3(L)(CN)(4)]center dot CH3OH}(n) (1) [L = 1-(N-acetopyridinine)-2-aminoethane], has been isolated using a one-pot reaction of the building components and was characterized. The crystal structure consists of [(CuL)-L-II](2+) units and copper(I) ions bridged by mu-CN anions. The copper(II) center of the CuN5 chromophore displays a square pyramidal coordination geometry provided by three N atoms of the tridentate Schiff base and two N atoms of mu-NC ions, while the copper(I) centers adopt a trigonal-planar geometry. Three copper centers are interconnected through mu-CN/mu-NC via {-Cu-1(L)(mu-NC)(2)Cu-2(mu-CN)Cu-3(mu-NC)-} units to form 2-D polymeric ribbons parallel to the b-axis. These 2-D polymeric ribbons in the crystalline state are further stabilized through pi center dot center dot center dot pi stacking interactions. Hirshfeld surface analysis was performed to gain additional insight into the interactions responsible for the packing of 1. Variable-temperature magnetic susceptibility studies showed a weak ferromagnetic interaction among the copper centers in 1 through cyanide bridges with J = 1.28 cm(-1).