Crystal Engineering of Mixed-Metal Ru–Ag Coordination Networks by Using the trans-RuCl2(pyz)4 (pyz=pyrazine) Building Block This work was supported by MURST within the project “Solid Supermolecules” 2000–2001 and by CSMTBO-CNR Center.

Three structural motifs have been obtained by using the novel building block trans-RuCl2(pyz)4 with different silver salts: A two-dimensional network with an unprecedented double-honeycomb topology, a three-dimensional array with the rutile (6,3) structure, and an interesting tetragonal network with both Ru and Ag in octahedral environments, which can be related to the rock-salt topology (see picture).