Using Pyridinyl-Substituted Diaminotriazines to Bind Pd(II) and Create Metallotectons for Engineering Hydrogen-Bonded Crystals

The pyridinyl groups of pyridinyl-substituted diaminotriazines 3a,b and 4a,b can bind metals, and the diaminotriazinyl (DAT) groups serve independently to ensure that the resulting complexes can participate in intercomplex hydrogen bonding according to characteristic motifs. As planned, ligands 3a,b and 4a,b form trans square-planar 2:1 complexes with PdCl2, and further association of the complexes is directed in part by hydrogen bonding of the DAT groups. Similarly, ligands 3a,b and 4a,b form cationic square-planar 4:1 complexes with Pd(BF4)2, Pd(PF6)2, and Pd(NO3)2, and the complexes again typically associate by hydrogen bonding of the peripheral DAT groups. The observed complexes have predictable constitutions and shared structural features that result logically from their characteristic topologies and the ability of DAT groups to engage in hydrogen bonding. These results illustrate the potential of a hybrid inorganic/organic strategy for constructing materials in which coordinative bonds to metals are used in conjunction with other interactions, both to build the molecular components and to control their organization.