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Structures of polynuclear complexes of palladium(II) and platinum(II) formed by slow hydrolysis in acidic aqueous solution

Torapava, Natallia and Elding, Lars Ivar and Mändar, Hugo and Roosalu, Kaspar and Persson, Ingmar (2013). Structures of polynuclear complexes of palladium(II) and platinum(II) formed by slow hydrolysis in acidic aqueous solution. Dalton Transactions: an international journal of inorganic chemistry [incorporating Acta Chemica Scandinavica]. 42:21, 7755-7760
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Official URL: http://dx.doi.org/10.1039/c3dt32859g

Abstract

The aqua ions of palladium(II) and platinum(II) undergo extremely slow hydrolysis in strongly acidic aqueous solution, resulting in polynuclear complexes. The size and structures of these species have been determined by EXAFS and small angle X-ray scattering, SAXS. For palladium(II), the EXAFS data show that the Pd-O and Pd···Pd distances are identical to those of crystalline palladium(II) oxide, but the intensities of the Pd···Pd distances in the Fourier transform at 3.04 and 3.42 Å are significantly lower compared to those of crystalline PdO. Furthermore, no Pd···Pd distances beyond 4 Å are observed. These observations strongly indicate that the polynuclear palladium(II) complexes are oxido amd hydroxido-bridged species with the same core structure as solid palladium(II) oxide. Based on the number of Pd···Pd distances, as derived from the EXAFS data, their size can be estimated to be approximately two unit cells, or ca. 1.0 nm3. For platinum(II), EXAFS data of the polynucler species formed in the slow hydrolysis process show Pt-O and Pt···Pt dist identical to those of amorphous platinum(II) oxide, precipitating from the solution studied. The Pt···Pt distances are somewhat different from those reported for crystalline platinum(II) oxide. The polynuclear platinum(II) complexes have a similar structure to the palladium ones, but they are somewhat larger, with an estimated diameter of 1.5-3.0 nm. It has not been possible to precipitate any of these species by ultracentrifugation. They are detectable by SAXS, indicating diameters between 0.7 and 2 nm, in excellent agreement with the EXAFS observations. The number of oxido- relative to hydroxido bridges will increase with increasing size of the complex. The charge of the complexes will remain about the same, +4, at growth, with approximate formulas [Pd10O4(OH)8(H2O)12]4+ and [Pt14O8(OH)8(H2O)12]4+ for complexes with a size of 2 and 3 unit cells of the corresponding solid metal oxide, respectively. Their high ionic charge in acidic aqueous solution will result in a stabilizing hydration shell.

Authors/Creators:Torapava, Natallia and Elding, Lars Ivar and Mändar, Hugo and Roosalu, Kaspar and Persson, Ingmar
Title:Structures of polynuclear complexes of palladium(II) and platinum(II) formed by slow hydrolysis in acidic aqueous solution
Series/Journal:Dalton Transactions: an international journal of inorganic chemistry [incorporating Acta Chemica Scandinavica] (1477-9226)
Year of publishing :2013
Volume:42
Number:21
Page range:7755-7760
Number of Pages:6
Publisher:Royal Society of Chemistry Publishing
ISSN:1477-9226
Language:English
Publication Type:Journal article
Refereed:Yes
Article category:Scientific peer reviewed
Version:Published version
Full Text Status:Public
Agris subject categories.:X Agricola extesions > X50 Chemistry
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 104 Chemical Sciences > Inorganic Chemistry
Agrovoc terms:Chemistry, Ions, Platinum, Hydrolysis, Hydration, Chemical structure
Keywords:Aqua ions, Palladium, Platinum, Hydrolysis, Hydration structure, Chemistry
URN:NBN:urn:nbn:se:slu:epsilon-e-1875
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-1875
Additional ID:
Type of IDID
Web of Science (WoS)000318792400030
DOI10.1039/c3dt32859g
ID Code:11069
Faculty:NL - Faculty of Natural Resources and Agricultural Sciences (until 2013)
Department:(NL, NJ) > Dept. of Chemistry (until 131231)
Deposited By: SLUpub Connector
Deposited On:25 Apr 2014 11:31
Metadata Last Modified:16 Feb 2015 07:30

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