Silver(I) polymeric coordination frameworks assembled with the new multimodal ligand 2,2 '-azobispyrazine

The synthesis of the new polyfunctional ligand 2,2'-azobispyrazine (azpyz), able to bind up to four different metal centres, and the self-assembly of polymeric coordination networks from different Ag(I) salts have been carried out. Four different structural types of polymeric species have been characterized: [Ag(azpyz)(2)] ClO4 (1a) and [Ag(azpyz)(2)] BF4 (1b) contain 1D helical chains, [Ag(azpyz)(2)] SbF6.0.5CH(2)Cl(2) ( 2) is comprised of undulating 2D layers of (4,4)-topology, [Ag-2 (azpyz) (H2O)] (BF4)(2) (3) consists of 2D sheets, containing mu(4)-eta(6)- azpyz ligands, with two distinct types of metal centres, and [Ag-4 (azpyz)(3)] (ClO4)(4) (4) is a complex 3D network, exhibiting mu(4)-eta(6)-azpyz and mu(4)-eta(5)-azpyz ligands, with four different types of Ag centres. In these compounds the azpyz ligands show varied bonding modes, using from 2 up to all 6 of its N-donor atoms. Most of the silver metal centres exhibit high coordination numbers ( up to 5 and 6)