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

Two copper alkylenediphosphonates, Cu 2 [(O 3 PC 4 H 8 PO 3 )(H 2 O) 2 ]·2H 2 O ( 1 ) and Cu 2 [(O 3 PC 5 H 10 PO 3 )(H 2 O) 2 ]·2.8H 2 O ( 2 ), have been synthesized and their crystal structures solved from X-ray powder data. Compound 1 is monoclinic, C 2/ 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 CuO 4 (OH 2 ) 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.