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The Palladium( II )‐Substituted, Lone Pair Containing Tungstoarsenates( III ) [Na 2 (H 2 O) 2 PdWO(H 2 O)(α‐AsW 9 O 33 ) 2 ] 10– and [Cs 2 Na(H 2 O) 8 Pd 3 (α‐AsW 9 O 33 ) 2 ] 9–
Author(s) -
Bi LiHua,
Kortz Ulrich,
Keita Bineta,
Nadjo Louis,
Daniels Lee
Publication year - 2005
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200500128
Subject(s) - chemistry , monoclinic crystal system , crystallography , triclinic crystal system , crystal structure , palladium , denticity , aqueous solution , stereochemistry , catalysis , biochemistry
The monopalladium( II )‐substituted [Na 2 (H 2 O) 2 PdWO(H 2 O)(α‐AsW 9 O 33 ) 2 ] 10– ( 1 ) and the tripalladium( II )‐substituted [Cs 2 Na(H 2 O) 8 Pd 3 (α‐AsW 9 O 33 ) 2 ] 9– ( 2 ) were synthesized in aqueous acidic medium (pH 4.8) by reaction of Pd 2+ ions with [As 2 W 19 O 67 (H 2 O)] 14– and [α‐AsW 9 O 33 ] 9– , respectively. The dimeric polyanions 1 and 2 were characterized by complete elemental analysis, FTIR, and electrochemistry. Single‐crystal X‐ray analysis was carried out on Cs 3 Na 7 [Na 2 (H 2 O) 2 PdWO(H 2 O)(α‐AsW 9 O 33 ) 2 ] · 1.5NaCl · 22H 2 O ( 1a ), which crystallizes in the triclinic system, space group P $\bar {1}$ , with a = 13.2465(16) Å, b = 16.873(2) Å, c = 23.080(3) Å, α = 107.315(2)°, β = 95.025(3)°, γ = 98.040(3)°, and Z = 2; Cs 3 Na 6 [Cs 2 Na(H 2 O) 8 Pd 3 (α‐AsW 9 O 33 ) 2 ] · NaCl · 15H 2 O ( 2a ) crystallizes in the monoclinic system, space group P 2 1 /m , with a = 13.1842(5) Å, b = 19.6584(7) Å, c = 18.2377(6) Å, β = 100.7660(10)°, and Z = 2. Polyanion 1 is composed of two [α‐AsW 9 O 33 ] 9– fragments connected by a WO(H 2 O) unit, one square‐planar palladium atom and two sodium ions, leading to a sandwich‐type structure with C s symmetry. Polyanion 2 also consists of two [α‐AsW 9 O 33 ] 9– moieties, but these are linked by three equivalent, square‐planar Pd 2+ ions, one sodium ion and two cesium ions, leading to a sandwich‐type structure with C 2 v symmetry. A cyclic voltammetric study of polyanion 2 in a pH 5 medium shows a Pd 0 deposition process on the glassy carbon electrode surface. The corresponding wave and the waves for the tungsten redox processes could be separated clearly. The thickness of the film increases with the number of potential cycles or the duration of potentiostatic electrolysis. The deposited film proved to be very stable and efficient in the electrocatalytic reduction of dioxygen. Polyanion 1 was not sufficiently stable in solution to warrant electrochemical characterization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)