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

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 1 H NMR and 13 C 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) A, b ) 5.821(2) A, c ) 28.982(9) A, and V ) 1319.7(7) A 3 . 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)‚1.5H2 O( III), Mn5(OH)2(O3PC6H4OC6H4PO3)2‚2H2 O( IV), Fe(HO3PC6H4OC6H4PO3)‚0.5H2 O( V), Co2(O3PC6H4OC6H4PO3)‚2H2O (VI), Ni2(O3PC6H4OC6H4PO3)‚3H2 O( VII), Ni2(O3PC6H4OC6H4PO3)‚2H2 O( VIII), Cu2(O3PC6H4OC6H4PO3 )( IX), Zn2(O3PC6H4OC6H4PO3 )( X), and Zn(HO3PC6H4OC6H4PO3H) (XI). Compound IX crystallizes in an orthorhombic