Über Komplexverbindungen der Elemente der IV. Gruppe. III. Über Blei(IV)‐phosphatverbindungen

Abstract

Blei(IV)‐acetat reagiert mit Phosphorsäure nicht zu binären Blei(IV)‐phosphaten, sondern zu Phosphatoblei(IV)‐säuren; mit „wasserfreier”︁ Säure entsteht H2[Pb(H2PO4)6], mit wasserhaltiger Säure (H2O‐Gehalt < 40%) höhermolekulare H2[Pb(H2PO4)2(HPO4)2]. Die Primärreaktion ist als Komplexbildung zwischen Pb(OCOCH3)4 und H3PO4 zu formulieren, an die sich besonders oberhalb Raumtemperatur Ligandenaustausch über isolierbare Zwischenprodukte, z. B. H2[Pb(H2PO4)4(OCOCH3)2] zu den verbrückten Phosphatoblei(IV)‐säuren anschließt. Aus den bei der Elektrolyse von wasserhaltiger Phosphorsäure an Bleielektroden sich bildenden Elektrolytlösungen wurde ebenfalls H2[Pb(H2PO4)2(HPO4)2] gewonnen. Die bei Raumtemperatur recht hydrolysebeständigen Verbindungen ergeben mit Hydroxidlösungen Salze, z. B. M2[Pb(H2PO4)2(HPO4)2] · 2 H2O (M  K, NH4).

The Effect of Phosphoric Acid on the Positive Electrode in the Lead‐Acid Battery: III . Mechanism

“…Several authors (4)(5)(6) have formed these complexes both chemically and electrochemically, but such complexes apparently occur only at HsPO4 concentrations above about 0.8% (10 g/l) in 35% H2SO4 (6). Several authors (4)(5)(6) have formed these complexes both chemically and electrochemically, but such complexes apparently occur only at HsPO4 concentrations above about 0.8% (10 g/l) in 35% H2SO4 (6).…”

“…A potentially troublesome mechanism is formation of soluble Pb(IV) phosphate complexes. Several authors (4)(5)(6) have formed these complexes both chemically and electrochemically, but such complexes apparently occur only at HsPO4 concentrations above about 0.8% (10 g/l) in 35% H2SO4 (6). Bullock and McClelland (1) observed a change in the kinetics of the PbOJPbSO4 couple at this same H~PO~ concentration, and much of the lead-acid battery patent literature recommends H3PO4 concentrations at or below this level (7)(8)(9).…”

The Effect of Phosphoric Acid on the Positive Electrode in the Lead Acid Battery

“…Several authors have found lead(IV) complexes with phosphate which can be produced both chemically and electrochemically (21)(22)(23)(24). Amlie and Berger (25) have noted that a soluble lead(IV) species can be detected polarographically in sulfuric acid only if phosphoric acid is present.…”

A Rotating Ring‐Disk Electrode Study of Soluble Lead (IV) Species in Sulfuric Acid Solution

“…Previous workers (4)(5)(6)(7)(8) have demonstrated that the presence of H3PO4 increases the solubility of Pb(IV) in H2SO4 due to the formation of relatively stable Pb(IV) phosphate complexes. Addition of 0.5 w/o H3PO4 to the sulfuric acid effects the performance of the PbSO4/PbO2 electrode, as previously reported (13), and as seen from Fig.…”