| Autor: |
Harmening, Thomas, Matar, Samir F., Fehse, Constanze, Klenner, Steffen, Eckert, Hellmut, Kösters, Jutta, Pröbsting, Wilma, Seidel, Stefan, Pöttgen, Rainer |
| Zdroj: |
Zeitschrift für Naturforschung B; January 2024, Vol. 79 Issue: 1 p1-12, 12p |
| Abstrakt: |
The TiMnSi2-type (space group Pbam) germanides ScTGe2(T= Fe, Co, Ru, Rh) were synthesized from the elements by arc-melting. Single crystals were grown by annealing sequences of the arc-melted buttons in an induction furnace. The structures of ScFeGe2, ScRuGe2and ScRhGe2were refined from single-crystal X-ray diffraction data. In ScRuGe2, the ruthenium atoms have distorted octahedral germanium coordination (242–268 pm Ru–Ge). Three trans-face-sharing octahedra form a sub-unit which is condensed via common edges in cdirection and connected viacommon corners with four adjacent blocks, forming a three-dimensional [RuGe2type] substructure. The two crystallographically independent scandium sites have coordination numbers 15 (Sc1@Ge8Ru4Sc3) and 17 (Sc2@Ge7Ru6Sc4). Electronic band structure calculations for ScCoGe2and ScRuGe2show a net charge transfer from the scandium to the transition metal and germanium atoms, leading to a description with polyanionic networks Scδ+[TGe2]δ−. The two crystallographically independent Sc sites are easily distinguishable by 45Sc magic-angle spinning (MAS)-NMR spectroscopy. Isotropic chemical shift values and nuclear electric quadrupolar interaction parameters were deduced from an analysis of the triple-quantum (TQ)-MAS NMR spectra. The electric field gradient parameters deduced from these experiments are in good agreement with quantum-chemical calculations using the Wien2kcode. Likewise, the two crystallographically independent iron sites in ScFeGe2could be discriminated in the 57Fe Mößbauer spectra through their isomer shifts and quadrupole splitting parameters: δ= 0.369(1) mm s−1and ∆EQ= 0.232(2) mm s−1for Fe1 and δ= 0.375(2) mm s−1and ∆EQ= 0.435(4) mm s−1for Fe2 (data at T= 78 K). |
| Databáze: |
Supplemental Index |
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