Starting generally with a 4:6:3 molar ratio of Pt, Sn, and R (where R = La–Sm), with or without the application of a NaCl flux, seven ternary compounds were obtained as single crystals. The platinides Pt4Sn6R3 (R = La–Nd) crystallize with the Pt4Ge6Pr3 type of structure (oP52, Pnma, a = 27.6–27.8 Å, b = 4.59–4.64 Å, c = 9.33–9.40 Å). With R = Pr, Pt4Sn6Pr3–x (oP52, Pnma, a = 7.2863(3) Å, b = 4.4909(2) Å, c = 35.114(1) Å) is also obtained, which might be considered a high-temperature polymorph with disorder on the Sn- and Pr-sites. For R = Nd and Sm, a structurally related isostructural series with a slightly different composition Pt3Sn5 R 2–x (oP52, Cmc21, a = 4.50–4.51 Å, b = 26.14–26.30 Å, c ≈ 7.29 Å) has been observed, together with Pt7Sn9Sm5 (oS42, Amm2, a = 4.3289(5) Å, b = 28.798(4) Å, c = 7.2534(9) Å) under the same conditions. The latter exhibits the rare Zr5Pd9P7-type structure, linking polar intermetallics to metal phosphides, in accord with P7Pd9Zr5Pt7Sn9Sm5. All structures may be described in terms of either negative Pt/Sn networks encapsulating positive R atoms, or {PtSn x } clusters (x = 5, 6, or rarely 7) sharing vertices and edges with R in the second coordination sphere and with considerable heterometallic Pt–R bonding contributions.
YAu (triyttrium tetragold) and YAu (tetradecayttrium henpentacontagold), two binary representatives of Au-rich rare earth (R) systems crystallize with the space groups R-3 and P6/m, adopting the PuPd and GdAg structure types, respectively (Pearson symbols hR42 and hP65). A variety of binary R-Au compounds have been reported, although only a few have been investigated thoroughly. Many reports lack information or misinterpret known compounds reported elsewhere. The PuPd type is fairly common for group 10 elements Ni, Pd, and Pt, while Au representatives are restricted to just five examples, i.e. CaAu, PrAu, NdAu, GdAu, and ThAu. SmAu is suspected to be SmAu due to identical symmetry and close unit-cell parameters. The PuPd structure type allows for full substitution of the position of the rare earth atom by more electronegative and smaller elements, i.e. Ti and Zr. The GdAg type instead is more common for the group 11 metals, while rare representatives of group 12 are known. YAu can be represented as a tunnel structure with encapsulated cations and anionic chains. Though tunnels are present in YAu, this structure is more complex and is best described in terms of polyhedral `pinwheels' around the tunnel forming polyhedra along the c axis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.