Structural investigation of ScAuSi and ScAuGe using 45Sc solid state NMR

The hexagonal scandium compounds ScAuSi (P (6) over bar m2, a = 421.7(l), c = 680.7(1) pm) and ScAuGe (P6(3)mc a 431.03(9), c = 685.5(1) pm) were synthesized in X-ray pure form via arc-melting of the elements. The structures are derived from the AlB2-type. The gold and silicon (germanium) atoms build up strongly puckered layers of Au3Si3 and Au3Ge3 hexagons. Due to a different puckering pattern and stacking sequence of the hexagons, the ScAuGe structure has one and the ScAuSi structure two crystallographically independent scandium sites, which can be unambiguously distinguished on the basis of Sc-45-Si-29 magnetic dipole-dipole interactions measured in a site selective fashion on an isotopically enriched material by solid state NMR.