Silver(i) polymeric coordination frameworks assembled with the new multimodal ligand2,2′-azobispyrazine

Abstract

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]SbF₆·0.5CH₂Cl₂ (2) is comprised of undulating 2D layers of (4,4)-topology, [Ag₂(azpyz)(H₂O)](BF₄)₂ (3) consists of 2D sheets, containing μ₄-η⁶-azpyz ligands, with two distinct types of metal centres, and [Ag₄(azpyz)₃](ClO₄)₄ (4) is a complex 3D network, exhibiting μ₄-η⁶-azpyz and μ₄-η⁵-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).