Anion-Directed Self-Assembly in Coordination Networks: Architectural Control via Cooperative Noncovalent Interactions

The self-assembly of a new flexible tritopic pyrazine-pyridine ligand (pz-3-py) with HgX2 (X = Cl, Br) was investigated. The results show that coordinated chloride and bromide anions play different roles, and two architecturally different coordination polymers were obtained with the anions used. Where X = Cl, in [Hg(mu(3)-pz-3-py)Cl-2](n) (1), the 2D network is isolated, while for X = Br, in [Hg(mu-pz-3-py)Br-2](n) (2), a 1D zigzag chain is constructed. Our results show that noncovalent interactions such as hydrogen bond, halogen center dot center dot center dot halogen, and halogen center dot center dot center dot pi interactions, when acting cooperatively, are driving forces for the selection of different structures.