Ga0.62(3)Sb0.38(3)Pd3, tetragonal, P4/mbm (no. 127), a = 5.5036(2) Å, c = 7.9990(3) Å, V = 242.29(3) Å3, Z = 4, Rp = 0.0168, Rwp = 0.0291, T = 295 K.
The crystal structure is shown in the figure. Tables 1 and 2 contain details on crystal structure and measurement conditions and a list of the atoms including atomic coordinates and displacement parameters.
|Sample, setting:||Grey powder, transmission geometry|
|Wavelength, μ:||Cu Kα1 radiation, (1.54056 Å), 214.6 mm−1|
|Diffractometer, scan mode:||Huber Guinier G670, step scan (0.005°)|
|2θ range / data points:||21–100.3°, 15861|
|No(hkl), N(param):||82, 22|
|Programs:||WinCSD , Diamond |
aOccupancy: 0.62(3), bOccupancy: 0.38(3).
Source of materials
New palladium compound with gallium and antimony, Ga0.62(3)Sb0.38(3)Pd3, was synthesized from elemental palladium (granules, ChemPur, 99.95%), gallium (pellets, ChemPur, 99.9999%) and antimony (shots, ChemPur, 99.9999%) by arc melting in a glove box (Ar atmosphere; O2 and H2O content below 1 ppm). Sample with a nominal composition Ga14Sb11Pd75, placed in alumina crucible and evacuated quartz glass tube, was annealed at 1123 K (48 h) and then at 773 K (408 h) and subsequently quenched in water. For the XRPD analysis the sample was filed and additionally annealed at 773 K for 24 h to remove residual strain. According to the obtained results, formation of the new ternary phase was detected.
The crystal structure of Ga0.62(3)Sb0.38(3)Pd3 was refined from XRPD data.
Ga0.62(3)Sb0.38(3)Pd3 crystallizes in the Pt3Ga structure type . There is no binary phase with composition 3:1 in the Ga–Pd system , while Pt3Al and Pt3Ga exist in three modifications  – high temperature cubic (Cu3Au-type structure, Pm3̄m, cP4), intermediate (U3Si-type structure, I4/mcm, tI16) and low temperature (Pt3Al-type structure, P4/mbm, tP16). The new ternary phase behaves similar to the binary platinum representative. Preliminary information on this phase was presented in .
Coordination environments of Pd1, Pd2, Ga1/Sb1 may be described as distorted tetragonal prisms with four additional atoms centering side faces (CN = 12). In the case of Pd3, the coordination polyhedron is also a distorted tetragonal prism, but with five additional atoms – four are situated opposite side faces and one is centering an edge (CN = 13).
In the crystal structure of Ga0.62(3)Sb0.38(3)Pd3 the interatomic Pd–Pd distances are not significantly increased in comparison with elemental palladium (by 0.6% for Pd1, 2.3% for Pd2, 2.5% for Pd3). Thus, palladium atoms are not well isolated. This feature does not allow to consider the title compound as a good potential catalytic material for the selective semi-hydrogenation of acetylene .
Dr. Horst Borrmann, Dr. Yurii Prots, Mr. Steffen Hückmann are acknowledged for XRPD experiments. OM is grateful to Dr. Lev Akselrud for help during crystal structure refinement.
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©2018 Oksana Matselko et al., published by De Gruyter, Berlin/Boston
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