Reaction of copper salts with 1,4-phenylenebis(phosphonic acid) yielded a conventional layered compound, Cu(2)[(O(3)PC(6)H(4)PO(3))(H(2)O)(2)], while a similar reaction with 4,4'-biphenylenebis(phosphonic acid) resulted in a new lamellar structure with composition Cu[HO(3)P(C(6)H(4))(2)PO(3)H]. The structures of these compounds were solved ab initio by using X-ray powder diffraction data. The crystals of the phenylenebis(phosphonate) compound are monoclinic, space group C2/c, with a = 18.8892(4) Å, b = 7.6222(2) Å, c = 7.4641(2) Å, beta = 90.402(2) degrees, and Z = 4. The layer structure in this case is similar to that in copper phenylphosphonate, Cu[O(3)PC(6)H(5)]. The metal atoms display a distorted square pyramidal geometry where four of the coordination sites are occupied by the phosphonate oxygens. The remaining site is filled by an oxygen atom of the water molecule. Adjacent metal-O(3)PC layers are covalently pillared by the phenyl group of the phosphonates to create a 3-dimensional structure. Cu[HO(3)P(C(6)H(4))(2)PO(3)H] is triclinic, space group P&onemacr;, with a = 4.856(2) Å, b = 14.225(5) Å, c = 4.788(2) Å, alpha = 97.85(1) degrees, beta = 110.14(1) degrees, gamma = 89.38(1) degrees, and Z = 1. The structure in this case, ideally consists of linear chains of copper atoms. The copper atoms are bridged by centrosymmetrically related phosphonate groups utilizing two of their oxygen atoms. This binding mode leads to square planar geometry for the copper atoms. The third oxygen atom of the phosphonate is protonated and is involved in linking adjacent linear chains through hydrogen bonds. At the same time, these hydroxyl oxygens interact weakly (Cu-O = 3.14 Å) with the copper atoms of the adjacent chain. Considering these long Cu-O interactions, the geometry of the copper atom may be described as distorted square bipyramidal. As in the phenylphosphonate structure, the biphenyl groups covalently link the Cu-O(3)PC networks in the perpendicular direction.

Two new lamellar metal phosphonates, zinc phenylenebis(phosphonate), Zn2[(O3PC6H4PO3)(H2O)2] (1), and zinc biphenylylenebis(phosphonate), Zn[HO3P(C6H4)2PO3H] (2), have been synthesized. The structures of these compounds were solved ab initio from X-ray powder diffraction data and refined by Rietveld methods. Compound 1 is orthorhombic:  space group Pnnm, a = 19.2991(6) Å, b = 4.8232(2) Å, c = 5.6545(2) Å, and Z = 2. The structure is layered, and its layer arrangement is similar to that in zinc phenylphosphonate. The zinc atoms are octahedrally coordinated. Two of the oxygens of the phosphonate group are involved in chelation and bridging the metal atoms. The third oxygen binds to only one metal atom. The sixth coordination site is occupied by a water molecule. The adjacent layers are bridged by the phenylene group of the bis(phosphonate). Compound 2 is triclinic:  space group P1̄, a = 9.5097(3) Å, b = 5.0074(2) Å, c = 14.2109(4) Å, α = 92.797(3)°, β = 99.725(3)°, γ = 92.003(3)°, and Z = 2. In this case the metal atoms are tetrahedrally coordinated by four oxygens, two from each of the phosphonate groups of the bis(phosphonate). The third oxygen of the phosphonate group is protonated and is not involved in metal binding. The structure consists of double chains with alternating Zn and P atoms connected to each other by phosphonate bridges. These double chains run along the b axis and are linked to similar chains along the a direction through hydrogen bonds involving P−OH groups. This arrangement leads to loosely bound metal−CPO3 networks in the ab plane which are bridged by the biphenylylene groups along the c axis. Thus in a broad sense this compound may also be considered as layered.

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