Diphosphonate ligands

Chromatographic analysis of these products demonstrates that these diphosphonates do not form a single 99mTc complex. For example, as many as 8-10 different "mTc species are resolvable on HPLC analysis [68-78]. Results from these and other studies indicate that 99mTc complexes with diphosphonate ligands form a mixture of oligomers and polymers that may include Sn [78], The only Tc-MDP structure, reported by Libson et al. [79], shows Tc-MDP to be a 1 1 polymer in which each Tc atom is coordinated to two diphosphonate ligands and each diphosphonate is coordinated to two Tc centers. 

Complexes of beryllium with phosphonate ligands have been extensively researched, mainly by potentiometry. The ligands investigated are as follows methylphosphonate (259, 260) chloromethyl-phosphonate (259) 2-aminopropane-l-phosphonate (259) methylene-diphosphonate (130, 260, 261) hexamethylenediphosphonate (259) l-hydroxyethane-l,l-diphosphonate (261) 1,1-dimethyl-1-amino-... 

Alexandratos, S. D., Trochimiczuk, A. W., Horwitz, E. P., Catrone, R. C., synthesis and characterization of a bifunctional ion exchange resin with polystyrene-immobilized diphosphonic acid ligands, J. Appl. Polymn. Sci. 61,1996,273-278. 

Unsaturated lactone 74 (Scheme 7.21) can be viewed as an oxygen heterocyclic analogue of 2-cyclohexenone, and it has recently been reported that catalytic 1,4-additions of Et2Zn to 74 can indeed be accomplished with high enantioselectivity. For adduct 76, Reetz achieved a remarkable 98% ee when employing ferrocene-based diphosphonate ligand 23 [48]. Using diphosphite 24, Chan et al. achieved an ee of 92% for the six-membered lactone 74 and a 56% ee for the five-membered lactone 25 [49c]. 

As part of a search for other ligands capable of adopting a square-planar configuration about a metal atom and thus potentially able to form stacked units our attention was drawn to the ligand H2P2052- (diphosphonate), usually abbreviated pop. Platinum complexes of this ligand - in particular [Pt2 (pop) i,] l - have already been subject to interesting studies of their luminescence, electronic, Raman and infrared spectra (12-161. Our initial objectives were to try to incorporate [Pt v(en)2X2]2+ (en =... 

Interesting results were obtained on the temperature dependence of the lifetime of an Eu(III) amino-diphosphonate complex, in H2O and D2O (Holz et al., 1990b). In both solvents, the lifetime decreases as temperature increases and this was ascribed to an additional (photoin-duced) deexcitation pathway due to some ligand energy levels. 

Amino-carboxylic and phosphonic acids are known to form open frameworks (i.e. porous materials), particularly with first-row transition metal ions. Lanthanide diphosphonates with 3D pillared-layer structure are also known and several classes of ligands such as sim-... 

The 119Sn NMR spectrum of the adduct PhSnCl3 (EtO)2POCH2CH2PO(OEt)2 at —90 °C consists of a triplet at —557 ppm and a doublet of doublets at —551 ppm with approximately 5 1 relative intensities. These resonances were attributed to isomers of the hexacoordinate complex301,1056. The first isomer has two equivalent phosphorus atoms in the tin coordination sphere and consists of cis-fac octahedra in accordance with the preferred cis -bridging behavior of the ethylene-diphosphonate ligand. The second isomer with nonequivalent phosphorus atoms consists of cis-mer octahedra125. 

Each methylenediphosphonate chelates not only to the Cu(II) site but also to one molybdenum center to produce a MoCu(03PCH2P03) subunit. The remaining two oxygen atoms link the diphosphonate to two molybdenum sites. Consequently, each diphosphonate ligand bonds to three binuclear Mo sites. In contrast to the structure of 9, all of the oxygen atoms of the methylenediphosphonate ligand of 12 are involved in bonding. 

H2O) 4+ tethers. The unusual cluster is constructed of a trinuclear unit of edgesharing MoOg octahedra, with two diphosphonate ligands decorating the periphery. Both diphosphonate moieties are monoprotonated at the pendant oxygen... 

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