Gallium(III) organophosphonate adducts with the bidentate amines 2,2 '-bipyridyl and 1,10-phenanthroline

A number of gallium(III) organophosphonates form adducts with the bidentate amines 2,2'-bipyridyl and 1,10-phenanthroline. These adducts contain a 1:2 :1 molar ratio of metal/phosphorus/amine and have the proposed formulations Ga(O3PR)(O2P(OH)R)(C10H8N2)(H2O)-H-. and Ga(O3PR)(O2P(OH)R)(C12H8N2)(H2O)- H-. (where R = CH3, C6H5, and CH2C6H5; C10H8N2 is 2,2'-bipyridyl and C12H8N 2 is 1,10-phenanthroline). Unlike the parent gallium(III) organophosphonate s, which conform to the general formula Ga(OH)(O3PR)(.)xH(2)O (x = 0 or 1), the amine adducts lack the hydroxo group, but contain the organophosphonat e ligand in the partially as well as fully deprotonated forms. All compound s were isolated from aqueous solutions as monohydrates, with the exception of the bipyridyl adduct of gallium(III) phenylphosphonate, which is anhydro us. TGA measurements suggest that for the hydrates, the water molecule is n ot coordinated to the metal. The bipyridyl adducts of gallium(III) phenylph osphonate and gallium(III) methylphosphonate, like the parent gallium(III) organophosphonates, are very likely layered, as indicated by the powder XRD patterns. In contrast, the corresponding phenanthroline adducts are non-la yered, and both the bipyridyl and phenanthroline adducts of gallium(III) be nzylphosphonate are amorphous solids. FTIR, powder XRD, TGA, XPS, solid sta te P-31/C-13 MAS-NMR and BET surface area data are presented and discussed. (C) 2001 Elsevier Science BN. All rights reserved.