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Synthesis and Characterization of a New Bisphosphonic Acid and Several Metal Hybrids Derivatives

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journal contribution
posted on 23.08.2004, 00:00 by M. Mar Gómez-Alcántara, Aurelio Cabeza, María Martínez-Lara, Miguel A. G. Aranda, Rafael Suau, Nattamai Bhuvanesh, Abraham Clearfield
Commercial bis-(4-bromophenyl)-ether, [BrC6H4]2−O, has been used to prepare 4-[4‘-(diethoxyphosphoryl)phenoxy]phenyl-phosphonic acid diethyl ester, [(CH3CH2)2O3P−C6H4]2−O, (I) following a slight modification of the Michaelis−Arbuzov reaction. The acid hydrolysis of I gave 4-(4‘-phosphonophenoxy)phenyl phosphonic acid, [H2O3P−C6H4]2−O (II), and both compounds have been characterized by 1H NMR and 13C NMR. The crystal structure of II has been determined by single-crystal X-ray diffraction. II crystallizes in an orthorhombic unit cell, space group Pbcn, with a = 7.822(3) Å, b = 5.821(2) Å, c = 28.982(9) Å, and V = 1319.7(7) Å3. The final R factor was R1 = 0.0614. The structure is layered, being held together through a hydrogen bonding network. II has been used as precursor in the syntheses of new metal (Mn, Fe, Co, Ni, Cu, and Zn) bisphosphonates. The syntheses were carried out using a fixed metal/bisphosphonic acid molar ratio of 2.1:1 and the influence of the pH in the reactions has been studied. Nine new compounds have been isolated:  Mn2(O3PC6H4OC6H4PO3)·1.5H2O (III), Mn5(OH)2(O3PC6H4OC6H4PO3)2·2H2O (IV), Fe(HO3PC6H4OC6H4PO3)·0.5H2O (V), Co2(O3PC6H4OC6H4PO3)·2H2O (VI), Ni2(O3PC6H4OC6H4PO3)·3H2O (VII), Ni2(O3PC6H4OC6H4PO3)·2H2O (VIII), Cu2(O3PC6H4OC6H4PO3) (IX), Zn2(O3PC6H4OC6H4PO3) (X), and Zn(HO3PC6H4OC6H4PO3H) (XI). Compound IX crystallizes in an orthorhombic unit cell, space group Pbcn, and unit cell parameters a = 8.1012(5) Å, b = 5.3109(3) Å, c = 29.2595(5) Å, and V = 1258.8(1) Å3. Its structure has been solved by ab initio powder diffraction and refined by the Rietveld method to RF = 0.042. IX has a pillared layer framework with highly distorted CuO5 groups sharing edges to give isolated dimers. XI was indexed in a monoclinic unit cell, space group P1121, with parameters a = 9.4991(9) Å, b = 5.0445(5) Å, c = 29.131(2) Å, γ = 91.945(7)°, and V = 1395.1(3) Å3. Its structure has been refined by the Rietveld method, RF = 0.054, since it is isostructural with the known compound, Zn[HO3P(C6H4)2PO3H]. All solids were also characterized by thermal analysis and IR and UV−Vis spectroscopies.