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Article

Lu5Pd4Ge8 and Lu3Pd4Ge4: Two More Germanides among Polar Intermetallics

1
Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, Via Dodecaneso 31, 16146 Genova, Italy
2
Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milano, Italy
3
Samara Center for Theoretical Materials Science (SCTMS), Samara State Technical University, Molodogvardeyskaya St. 244, Samara 443100, Russia
*
Author to whom correspondence should be addressed.
Crystals 2018, 8(5), 205; https://doi.org/10.3390/cryst8050205
Received: 20 April 2018 / Revised: 3 May 2018 / Accepted: 3 May 2018 / Published: 5 May 2018
(This article belongs to the Special Issue Compounds with Polar Metallic Bonding)
In this study, two novel Lu5Pd4Ge8 and Lu3Pd4Ge4 polar intermetallics were prepared by direct synthesis of pure constituents. Their crystal structures were determined by single crystal X-ray diffraction analysis: Lu5Pd4Ge8 is monoclinic, P21/m, mP34, a = 5.7406(3), b = 13.7087(7), c = 8.3423(4) Å, β = 107.8(1), Z = 2; Lu3Pd4Ge4 is orthorhombic, Immm, oI22, a = 4.1368(3), b = 6.9192(5), c = 13.8229(9) Å, Z = 2. The Lu5Pd4Ge8 analysed crystal is one more example of non-merohedral twinning among the rare earth containing germanides. Chemical bonding DFT studies were conducted for these polar intermetallics and showing a metallic-like behavior. Gathered results for Lu5Pd4Ge8 and Lu3Pd4Ge4 permit to described both of them as composed by [Pd–Ge]δ– three dimensional networks bonded to positively charged lutetium species. From the structural chemical point of view, the studied compounds manifest some similarities to the Zintl phases, containing well-known covalent fragment i.e., Ge dumbbells as well as unique cis-Ge4 units. A comparative analysis of molecular orbital diagrams for Ge26– and cis-Ge10– anions with COHP results supports the idea of the existence of complex Pd–Ge polyanions hosting covalently bonded partially polarised Ge units. The palladium atoms have an anion like behaviour and being the most electronegative cause the noticeable variation of Ge species charges from site to site. Lutetium charges oscillate around +1.5 for all crystallographic positions. Obtained results explained why the classical Zintl-Klemm concept can’t be applied for the studied polar intermetallics. View Full-Text
Keywords: polar intermetallics; symmetry reduction; chemical bond polar intermetallics; symmetry reduction; chemical bond
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MDPI and ACS Style

Freccero, R.; Solokha, P.; Proserpio, D.M.; Saccone, A.; De Negri, S. Lu5Pd4Ge8 and Lu3Pd4Ge4: Two More Germanides among Polar Intermetallics. Crystals 2018, 8, 205. https://doi.org/10.3390/cryst8050205

AMA Style

Freccero R, Solokha P, Proserpio DM, Saccone A, De Negri S. Lu5Pd4Ge8 and Lu3Pd4Ge4: Two More Germanides among Polar Intermetallics. Crystals. 2018; 8(5):205. https://doi.org/10.3390/cryst8050205

Chicago/Turabian Style

Freccero, Riccardo, Pavlo Solokha, Davide M. Proserpio, Adriana Saccone, and Serena De Negri. 2018. "Lu5Pd4Ge8 and Lu3Pd4Ge4: Two More Germanides among Polar Intermetallics" Crystals 8, no. 5: 205. https://doi.org/10.3390/cryst8050205

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