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Prikhodchenko, Petr V.; Привалов, В. И.; Tripol’skaya, T. A.; Ippolitov, E. G.

doi:10.1023/a:1012932808953

Cited by 4 publications

(2 citation statements)

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“…Potassium stannate K 2 SnO 3 ·3H 2 O, which dissolves in water as the hexahydroxystannate(IV) K 2 [Sn(OH) 6 ], gives a signal at δSn = −595.3 ppm, in agreement with some older literature data and more recent results for Rb 2 [Sn(OH) 6 ] with δSn = 590.5 ppm …”

Section: Resultssupporting

confidence: 89%

“…35 Potassium stannate K 2 SnO 3 •3H 2 O, which dissolves in water as the hexahydroxystannate(IV) K 2 [Sn(OH) 6 ], gives a signal at δSn = −595.3 ppm, in agreement with some older literature data 36 and more recent results for Rb 2 [Sn(OH) 6 ] with δSn = 590.5 ppm. 37 It is important to note in the present context that K 2 [Sn(OH) 6 ] obviously does not form a pyrophosphate complex in aqueous solution: The signal at δSn = 594.8 ppm obtained if Na 4 P 2 O 7 •10H 2 O is added to the solution of K 2 [Sn(OH) 6 ] shows no significant shift from the original position (pH 9 is established under these conditions). The same is true for the addition of Na 5 P 3 O 10 , which yields a solution of pH 10 (Figures 4a−c).…”

Section: ■ Introductionmentioning

confidence: 64%

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Pyrophosphate Complexation of Tin(II) in Aqueous Solutions as Applied in Electrolytes for the Deposition of Tin and Tin Alloys Such as White Bronze

2012

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Electrodeposition of tin and tin alloys from electrolytes containing tin(II) and pyrophosphates is an important process in metal finishing, but the nature of the tin pyrophosphate complexes present in these solutions in various pH regions has remained unknown. Through solubility and pH studies, IR and (31)P and (119)Sn NMR spectroscopic investigations of solutions obtained by dissolving Sn(2)P(2)O(7) in equimolar quantities of either Na(4)P(2)O(7)·10H(2)O or K(4)P(2)O(7) the formation of anionic 1:1 complexes {[Sn(P(2)O(7))]}(n)(2n-) has now been verified and the molecular structures of the monomer (n = 1) and the dimer (n = 2) have been calculated by density functional theory (DFT) methods. Whereas the alkali pyrophosphates Na/K(4)P(2)O(7) give strongly alkaline aqueous solutions (pH ∼13), because of partial protonation of the [P(2)O(7)](4-) anion, the [Sn(P(2)O(7))](2-) anion is not protonated and the solutions of Na/K(2)[Sn(P(2)O(7))] are almost neutral (pH ∼8). The monomeric dianion appears to have a ground state with C(2v) symmetry with the Sn atom in a square pyramidal coordination and the lone pair of electrons in the apical position, while the dimer approaches C(2) symmetry with the Sn atoms in a rhombic pyramidal coordination, also with a sterically active lone pair. A comparison of experimental and calculated IR details favors the monomer as the most abundant species in solution. With an excess of pyrophosphate, 3:2 and 2:1 complexes (P(2)O(7)):(Sn) are first formed, which, in the presence of more pyrophosphate, undergo rapid ligand exchange on the NMR time scale. The structure of the 2:1 complex [Sn(P(2)O(7))(2)](6-) was calculated to have a pyramidal complexation by two 1,5-chelating pyrophosphate ligands. Neutralization of these alkaline solutions by sulfuric or sulfonic acids (H(2)SO(4), MeSO(3)H), as also practiced in electroplating, appears to afford the tin(II) hydrogen pyrophosphates [Sn(P(2)O(7)H)](-) and [Sn(H(2)P(2)O(7))](0). The molecular structures of the mononuclear model units have also been calculated and were shown to have an unsymmetrical complexation and to feature trigonal pyramidal (pseudotetrahedral) coordination. NMR observations have shown that, contrary to the results obtained for Sn(II) compounds, Sn(IV) as present in K(2)SnO(3) or its hydrated form (K(2)Sn(OH)(6)) does not form a pyrophosphate complex in aqueous solution near pH 7. There is also no interference of sulfite.

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Section: Resultssupporting

confidence: 89%

Section: ■ Introductionmentioning

confidence: 64%