Synthesis and Crystal Structures of Copper(II) Diphosphonatoalkanes: C₄ and C₅

Abstract

Two copper alkylenediphosphonates, Cu2[(O3PC4H8PO3)(H2O)2]·2H2O (1) and Cu2[(O3PC5H10PO3)(H2O)2]·2.8H2O (2), have been synthesized and their crystal structures solved from X-ray powder data. Compound 1 is monoclinic, C2/m, with a = 20.035(6), b = 6.6713(2), and c = 4.3966(1) Å, β = 91.379(1)°, and Z = 2. Compound 2 is orthorhombic, Pmmn, with a = 22.3773(2), b = 6.7633(1), and c = 4.3529(1) Å, and Z = 2. Both structures consist of layers of CuO4(OH2)2 octahedra in which the layers are cross-linked by the alkyl chains into three-dimensional lattices. This pillared arrangement creates tunnels running parallel to the c-axis direction containing water molecules. Dehydration of the compounds is irreversible, but in the hydrated state, ammonia readily replaces the water.