A rational synthesis of ladder-like motif in zinc-methylphosphonate from a preformed coordination assembly

The study describes the synthesis of new hybrid zinc phosphonates, {Zn(O₃PMe)(4,4′-bipy)_0.5}·2H₂O (2), {Zn(O₃PMe)(1,2-bpe)_0.5}·H₂O (3) and Zn(O₃PMe)(Im) (4) [4,4′-bipyridine (4,4′-bipy), 1,2-bis(4-pyridyl)ethane (1,2-bpe) and imidazole (Im)] by hydro(solvo)thermal reaction (140–150 °C, 3 days) of a preformed coordination polymer, zinc bis(O-methyl methylphosphonate), Zn{OP(O)(OMe)Me}₂ (1) with an appropriate N-donor ligand. X-ray crystallographic studies reveal structural transformation of a linear chain zinc-phosphonate framework in 1 to a ladder motif in 2–4 which is constructed by corner sharing of ZnO₃N and CPO₃ tetrahedra. For 2 and 3, the bifunctional N-donor ligands act as linkers to afford the formation of a layered structure. The lattice water molecules in 2 form an infinite array of cyclic tetramers via O–H⋯O2(P) hydrogen bonding interactions and occupy the interlayer region.