SYNTHESIS AND X-RAY-POWDER STRUCTURES OF 2 LAMELLAR COPPER ARYLENEBIS(PHOSPHONATES)

Reaction of copper salts with 1,4-phenylenebis(phosphonic acid) yielde d a conventional layered compound, Cu-2[(O3PC6H4PO3)(H2O)(2)], while a similar reaction with 4,4'-biphenylenebis(phosphonic acid) resulted i n a new lamellar structure with composition Cu[HO3P(C6H4)(2)PO3H]. The structures of these compounds were solved ab initio by using X-ray po wder diffraction data. The crystals of the phenylenebis(phosphonate) c ompound are monoclinic, space group C2/c, with a = 18.8892(4) Angstrom , b = 7.6222(2) Angstrom, c = 7.4641(2) Angstrom, beta = 90.402(2)degr ees, and Z = 4. The layer structure in this case is similar to that in copper phenylphosphonate, Cu[O3PC6H5]. The metal atoms display a dist orted square pyramidal geometry where four of the coordination sites a re occupied by the phosphonate oxygens. The remaining site is filled b y an oxygen atom of the water molecule. Adjacent metal-O3PC layers are covalently pillared by the phenyl group of the phosphonates to create a 3-dimensional structure. Cu[HO3P(C6H4)(2)PO3H] is triclinic, space group <P(1)over bar>, with a = 4.856(2) Angstrom, b = 14.225(5) Angstr om, c = 4.788(2) Angstrom, alpha = 97.85(1)degrees, beta = 110.14(1)de grees, gamma = 89.38(1)degrees, and Z = 1. The structure in this case, ideally consists of linear chains of copper atoms. The copper atoms a re bridged by centrosymmetrically related phosphonate groups utilizing two of their oxygen atoms. This binding mode leads to square planar g eometry for the copper atoms. The third oxygen atom of the phosphonate is protonated and is involved in linking adjacent linear chains throu gh hydrogen bonds. At the same time, these hydroxyl oxygens interact w eakly (Cu-O = 3.14 Angstrom) with the copper atoms of the adjacent cha in. Considering these long Cu-O interactions, the geometry of the copp er atom may be described as distorted square bipyramidal. As in the ph enylphosphonate structure, the biphenyl groups covalently link the Cu- O3PC networks in the perpendicular direction.