Stabilities of the Divalent Metal Ion Complexes of a Short-Chain Polyphosphate Anion and Its Imino Derivative

Abstract

The stability constants of ML-type complexes of the two linear triphosphate ligand anion analogues triphosphate (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\text{P}}_{ 3} {\text{O}}_{10}^{5 - } $$\end{document}) and diimidotriphosphate (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\text{P}}_{ 3} {\text{O}}_{ 8} ( {\text{NH}})_{2}^{5 - } $$\end{document}) were investigated thermodynamically using potentiometric titrations according to Schwarzenbach’s procedure. The stability constants of the ML-type complexes of different divalent metal ions with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\text{P}}_{ 3} {\text{O}}_{ 8} ( {\text{NH}})_{2}^{5 - } $$\end{document} are larger than those of the corresponding complexes with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\text{P}}_{ 3} {\text{O}}_{10}^{5 - } $$\end{document} because of the greater basicity of the imino group. The order of the stability constants for the ML-type complexes follows the Irving–Williams order, indicating that only non-bridging oxygen atoms are coordinated directly to the different metal ions in both ligands, and that the imino groups cannot participate in coordination to the metal ions. In the complexation reactions of the Ca2+, Sr2+, Ba2+–\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\text{P}}_{ 3} {\text{O}}_{10}^{5 - } $$\end{document} and Cu2+, Zn2+, Ni2+–\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\text{P}}_{ 3} {\text{O}}_{ 8} ( {\text{NH}})_{2}^{5 - } $$\end{document} systems, each metal ion forms an enthalpically stable complex, and there was no suggestion of a conspicuous entropic effect based on the chelate effect. Monodentate complexes that are strongly coordinated with the ligands were there...

Manganese Oxide Catalyzed Hydrolysis of Polyphosphates

“…Figure S9d showed a higher amount of Cu 2+ /Zn 2+ /Mn 2+ uptake by δ-MnO 2 surface. Total P uptake by δ-MnO 2 in the presence of Cu 2+ , Zn 2+ , and Mn 2+ was also higher than that in the presence of Ca 2+ and Mg 2+ (Figure S9c), possibly due to the stronger affinity of Cu 2+ /Zn 2+ /Mn 2+ to phosphate groups and Mn oxide surface. , …”

“…Total P uptake by δ-MnO 2 in the presence of Cu 2+ , Zn 2+ , and Mn 2+ was also higher than that in the presence of Ca 2+ and Mg 2+ (Figure S9c), possibly due to the stronger affinity of Cu 2+ /Zn 2+ /Mn 2+ to phosphate groups and Mn oxide surface. 34,35 Hydrolysis of Ca-PolyP Solid Granules. The effect of polyP phase (solid vs dissolved) on its hydrolysis was also investigated in the presence of α-MnO 2 (Figure 7), as previous studies have suggested the abundant presence of scattered micron-sized Ca-polyP particles in marine sediments.…”

“…22 Ca 2+ may also possibly form strong bonds with phosphate groups to form surface ternary complexes and serve as a cation bridge. 34 Due to the larger ionic radius of Ca atom (1.14 Å) compared to Mn (0.67 Å), we consider the formation of monodentate Casurface complexes to be more likely (as opposed to bidentate Ca surface complexes). Similar ternary surface complexes might also form in the presence of other divalent cations such as Zn 2+ , Cu 2+ , and Mn 2+ , which can explain the enhanced hydrolysis of polyP in the presence of these cations.…”

Synthesis, protonation equilibrium and peculiar thermal decomposition behavior of cyclo-tri-μ-imidotetraphosphate

“…There have been several studies on the acid dissociation, complex formation and pyrolysis behaviors of short-chain imidophosphates and cyclo-μ-imidotriphosphates as six-membered compounds. [36][37][38][39][40][41][42] On the other hand, except for cyclotetra-μ-imidotetraphosphate anions as shown in Fig. S1, † 43,44 all four bridging atoms of which are nitrogen atoms, neither synthesis nor isolation has been reported for a series of cycloμ-imidotetraphosphates as an eight-membered compound.…”

“…[45][46][47][48][49][50][51] Consequently, the cyclo-diμ-imidotriphosphate sodium salt, Na 3 cP 3 O 7 (NH) 2 , in which one of the bridging nitrogen atoms in cyclo-tri-μ-imidotriphosphate sodium salt, Na 3 cP 3 O 6 (NH) 3 , was replaced by an oxygen atom, is applied to a starting material for the synthesis of diimidotriphosphate sodium salt, Na 5 P 3 O 8 (NH) 2 , which has a short chain molecular structure. 37,38,52 Similarly, Na 4 cP 4 O 9 (NH) 3 is expected to be used as a starting material for the synthesis of Na 6 P 4 O 10 (NH) 3 . In this study, a novel method and pH-controlled recrystallization for the synthesis of Na 4 cP 4 O 9 (NH) 3 were developed, and the dependence of the protonation equilibria of various cyclo-μ-imidotetraphosphate anions, cP 4 O 12−n (NH) n 4− (n = 0, 2, 3, 4), on the number of imino groups which constitute the ligand molecules was investigated by potentiometric titrations and 31 P NMR measurements.…”