Reference

A structural study on metal binding of gem-diphosphonates, bone growth regulators

A structural study on metal binding of gem-diphosphonates, bone growth regulators. Nardelli, M.; Pelizzi, G.; Staibano, G.; Zucchi, E. (Ist. Chim. Gen. Inorg., Univ. Parma, Parma 43100, Italy). Inorg. Chim. Acta, 80(6), 259-71 (English) 1983. CODEN: ICHAA3. ISSN: 0020-1693. DOCUMENT TYPE: Journal CA Section: 75 (Crystallography and Liquid Crystals) Section cross-reference(s): 13 The crystal structures of Na dichloromethylenediphosphonate tetrahydrate (I) and Ca dichloromethylenediphosphonate pentahydrate (II) detd. from single-crystal x-ray diffractometer data, are compared with those of other bone growth regulators (gem-diphosphonates and pyrophosphates). I is triclinic, space group P1, with a 11.27(2), b 9.18(2), c 5.91(1) ?, a 88.57(2)°, b 92.69(2)°, and g 90.58(2)°; Z = 1 (2 mols./Z). Final R = 0.0359 and Rw = 0.0453. The 2 crystallog. independent Na ions both show octahedral coordination, but, while one of them is coordinated by 2 couples of oxygens from 2 chelating diphosphonate anions plus a Cl atom and a water mol., the other is surrounded by 3 O atoms from 3 different diphosphonate anions and 3 water mols. Two couples of these octahedra, sharing edges, form tetrameric clusters joined together by diphosphonate bridges. II is orthorhombic, space group Pnma, with a 10.278(2), b 10.872(2), and c 11.899(2) ?; Z = 4; final R = 0.0389 and Rw = 0.0449.There are some commonly used reagents with their cas registry numbers 88416-51-7 and 88416-50-6 in this article. Ca is heptacoordinated by 2 O atoms from a diphosphonate anion acting as a bidentate chelating agent, and 5 water mols. The coordination polyhedron can be described as a distorted monocapped trigonal prism. Cl is not involved in coordination to the metal. In both compds. the diphosphonate anion interacts with the cation through deprotonated O atoms and assumes a nearly eclipsed conformation which gives a O...O bite distance as short as 3.06-3.27 ? which seems particularly suitable for bidentate chelation to Ca and is characteristic of this class of Ca phosphate metab. regulators. .