Designing neutral coordination networks with the aid of hydrogen bond mimicry using silver(i) carboxylates

Abstract

Parallels can be drawn between the structural chemistry of carboxylic acids and that of silver(I) carboxylates in which ‘Ag⁺ ions’ in the latter replace ‘H⁺ ions’ in the former. Both form ring and tape arrangements, which can be used effectively in crystal engineering to construct neutral networks. Silver(I) carboxylates, however, have the additional capacity to coordinate further ligands. Here we describe a series of network structures developed using a secondary building unit (SBU) based upon the carboxylate-bridged Ag₂ dimer, ‘Ag₂(CF₃CO₂)₂L₄’, where L is a neutral ditopic ligand. Use of L = 1,4-diazabicyclooctane, piperazine, or each of five different pyrazine derivatives leads to closely related lamellar structures of composition Ag₂(CF₃CO₂)₂L₂, which have been characterized by single crystal X-ray diffraction and whose bulk composition has been examined by elemental analysis and powder diffraction. The versatility and reliability of the silver(I) carboxylate linkage is also examined and compared with that of supramolecular synthons known for carboxylic acid building blocks.