Silver coordination polymers with tri- and hexacyanoethyl-functionalized macrocyclic ligands

Tri- and hexa-cyanoethyl functionalized 17- () and 42-membered () macrocyclic compounds were obtained by [1 + 1] (for ) or [2 + 2] (for ) cyclocondensation of the corresponding dialdehyde and diethylenetriamine, followed by hydrogenation by KBH4 and subsequent cyano-functionalization with acrylonitrile. They react with silver nitrate, leading to the formation of [AgL(1)](NO3) () and of the metal-organic coordination polymers [Ag2(NO3)2L(1)]n () and {[Ag2](NO3)2}n (). The complexes were characterized by elemental analysis, (1)H NMR, (13)C NMR, IR spectroscopies, and ESI-MS; moreover, , , and were also characterized by single crystal X-ray diffraction. The metal cation in is pentacoordinated with a N3O2 coordination environment; in , the metal cations display N4O2 octahedral and N2O3 square-pyramid coordination and in they are in square-planar N4 sites. In , the ligand acts as a pentadentate chelator, and in the other two cases, the ligands behave as octadentate chelators in a 1κ(3)N:κ(2)O,2κN,3κN,4κN (in ) or 1κ(3)N,2κ(3)N,3κN,4κN fashion (in ). The cyanoethyl strands of the ligands are directly involved in the formation of the 2D frameworks of and , which in the former polymer can be viewed as a net composed of hexametallic 36-membered macrocyclic rings and in the latter generates extra hexametallic 58-membered cyclic sets that form zig-zag layers. The thermal analytical and electrochemical properties of these silver complexes were also studied.