The high-temperature modification of ScRuSi - Structure, Si-29 and Sc-45 solid state NMR spectroscopy

摘要

A polycrystalline sample of the TiNiSi type low-temperature (LT) modification of ScRuSi was synthesized by arc-melting. Longer annealing in a sealed silica tube (6 weeks at 1270 K) followed by quenching led to the high-temperature (HT) phase. HT-ScRuSi adopts the ZrNiAI structure type: P (6) over bar 2m, a = 688.27(9), c = 336.72(5) pm, wR2 = 0.0861, 260 F-2 values, 14 variables. The striking structural building units are regular, tricapped trigonal prisms Sil@Ru3Sc6 and Si2@Ru6Sc3. Both polymorphs have been characterized by Si-29 and Sc-45 MAS-NMR spectroscopy. The local scandium environments in the two polymorphs are easily distinguished by their electric field gradient tensor values, in agreement with theoretically calculated values. (C) 2017 Elsevier Masson SAS. All rights reserved.