Bridging Solution and Solid-State Chemistry of Dicyanoaurate: The Case Study of Zn-Au Nucleation Units

The behavior in solution of the dicyanoaurate anion in the presence of other metal centers has so far been little explored, despite its importance in material science. The design and synthesis of systems with controlled coordination behavior, using chelating ligands and Zn^II, has allowed us to detect self-assembly and oligomerization in solution. This phenomenon has been studied with ¹³C and ¹H NMR, absorption and emission UV-vis spectroscopy, ESI-MS, and XAS at both the Au L₃-edge and Zn K-edge: all of these techniques confirm the presence of Au-Zn aggregation products. These fragments, resembling structural units in the solid state, reveal that coordination of dicyanoaurate to free sites around metal centers can occur at a lower concentration than those at which crystals start to form and at which aurophilic interactions are observed, forming the connection between solution species and solid-state architectures.