Complex Salts Containing [Pd(NH3)4]2+ Cations and WO42− and W7O246− Anions: The Precursors of Pd–W Metal Alloys

• Published in: Journal of structural chemistry 2020, Vol.61 (3), p.449-455
• Main Authors: Khranenko, S. P., Sukhikh, A. S., Komarov, V. Yu, Gromilov, S. A.
• Format: Article
• Language: English
• Subjects: Ammonia; Anions; Atomic; Atomic/Molecular Structure and Spectra; Cations; Chemistry; Chemistry and Materials Science; Crystal structure; Crystallography; Inorganic Chemistry; Molecular; Optical and Plasma Physics; Palladium; Physical Chemistry; Solid State Physics; Thermal decomposition; Unit cell; X ray powder diffraction
• ISSN: 0022-4766; 1573-8779
• DOI: 10.1134/S0022476620030117

Two crystal structures containing [Pd(NH 3 ) 4 ] 2+ cations and WO 4 2 − and W 7 O 24 6 − anions are studied. For the [Pd(NH 3 ) 4 ]WO 4 structure at 150 K the following crystallographic data are obtained: a = 7.4626(3) Å, c = 15.5718(8) Å, space group I 4 1 /amd, V = 867.20 Å 3 , Z = 4. With increasing temperature to 400 K, the unit cell parameters change in different directions: a increases by 0.032 Å, c decreases by 0.036 Å. The total increase in the unit cell volume is 5 Å 3 . In a range of 150 K to 400 K, the observed W-O distances decrease by 0.019 Å from 1.778(18) Å to 1.759(3) Å. For the [Pd(NH 3 ) 4 ] 3 W 7 O 24 ·4.4H 2 O structure at 298 K the crystallographic data are as follows: a = 8.3409(2) Å, b = 22.2654(6) Å, c = 10.5450(3) Å, β = 104.449(1)°, space group P 2 1 /m, V = 1896.41 Å 3 , Z = 2. In the heptatungstate anion the shortest are the W—O distances with the terminal O atoms (1.731–1.745 Å). The distances to the bridging O atoms connecting two W atoms are 1.930–2.406 Å; those connecting three W atoms are 1.882–2.234 Å, and those connecting four W atoms are 2.192–2.220 Å. It is shown that the [Pd(NH 3 ) 4 ] 3 W 7 O 24 ·4.4H 2 O structure has a pseudohexagonal motif in the a direction. The thermal decomposition of the salts is performed in the presence of LiH in the He atmosphere at 1273 K. The ex situ powder X-ray diffraction study reveals the formation of Pd–W alloys.