The three intermetallic compounds SrAuGa, BaAuAl and BaAuGa were synthesised from the elements in niobium ampoules. The Sr compound crystallises in the orthorhombic KHg -type structure (Imma, a=465.6(1), b=771.8(2), c=792.6(2) pm, wR =0.0740, 324 F values, 13 variables), whereas the Ba compounds were both found to crystallise in the cubic non-centrosymmetric LaIrSi-type structure (P2 3, BaAuAl: a=696.5(1) pm; wR =0.0427, 446 F values, 12 variables; BaAuGa: a=693.49(4) pm, wR =0.0717, 447 F values, 12 variables). The samples were investigated by powder X-ray diffraction and their structures refined on the basis of single-crystal X-ray diffraction data. The title compounds, along with references from the literature (CaAuAl, CaAuGa, CaAuIn, and SrAuIn), were characterised further by susceptibility measurements and Al and Ga solid-state NMR spectroscopy. Theoretical calculations of the density of states (DOS) and the NMR parameters were used for the interpretation of the spectroscopic data. The electron transfer from the alkaline-earth metals and the group 13 elements onto the gold atoms was investigated through X-ray photoelectron spectroscopy (XPS), classifying these intermetallics as aurides.

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The compounds Eu 2 Rh 3 Ga 9 and Eu 2 Ir 3 Ga 9 were synthesized by melting the elements in sealed tantalum tubes with subsequent annealing at 600 • C. Both gallides are isotypic with Y 2 Co 3 Ga 9 (space group Cmcm, Pearson symbol oC56, Z = 4) as evidenced by single crystal structure analysis: a = 12.9902(6), b = 7.6141(4), c = 9.7433(5) ˚ A, R F = 0.025, 617 structure factors, 42 variable parameters for Eu 2 Rh 3 Ga 9 , and a = 13.0371(7), b = 7.6017(4), c = 9.6972(6) ˚ A, R F = 0.032, 645 reflections, 42 variables for Eu 2 Ir 3 Ga 9. Magnetic susceptibility measurements as well as X-ray absorption spectra indicate the 4 f 7 electronic configuration of europium (Eu 2+) with significant ad-mixture of the 4 f 6 state in both compounds.

The silicide ScPdSi was synthesized from the elements by arc-melting. Its structure was refined from single crystal X-ray diffractometer data: Immm, LiCuP type, a = 397.12(6), b = 945.4(1), c = 1314.4(2) pm, wR = 0.0245, 578 F values and 29 parameters. The palladium atoms have slightly distorted tetrahedral silicon coordination and a condensation of these PdSi tetrahedra leads to a two-dimensional substructure which is condensed via Si pairs (234 pm Si-Si), forming the [PdSi] polyanionic network. The ScPdSi structure contains three crystallographically independent scandium sites with coordinations Sc1@PdSiSc, Sc2@PdSiSc and Sc3@PdSiSc. ScPdSi is a Pauli paramagnet with a low susceptibility of 2.9(5) × 10 emu mol at room temperature. The Si MAS-NMR spectrum confirms the presence of two crystallographically distinct sites in a 2 : 1 ratio. Likewise, the three crystallographic scandium sites are well-differentiated by threeSc MAS NMR signals in the expected 2 : 2 : 1 ratio. Unambiguous assignments could be made based on the comparison of the nuclear electric quadrupolar coupling parameters with predicted values from WIEN2k calculations.

The silicides RE 3Pd20Si6 (RE = Sc, Y and Lu) were synthesized from the elements by arc-melting. The structures of Y3Pd20Si6 and Lu3Pd20Si6 were refined from single crystal X-ray diffractometer data: Mg3Ni20B6 type, F m 3 ‾ m $Fm\bar{3}m$ , a = 1216.04(8) pm, wR = 0.0328, 219 F 2 values, 14 variables for Y3Pd20Si6 and a = 1211.69(10) pm, wR = 0.0374, 217 F 2 values, 14 variables for Lu3Pd20Si6. The isotypy of Sc3Pd20Si6 was confirmed on the basis of a Guinier powder pattern (a = 1202.8(3) pm). The RE 3Pd20Si6 structures contain two crystallographically independent RE sites with relatively large coordination numbers, i.e. RE1@Pd16 and RE2@Pd12Si6. These polyhedra are arranged in a CaF2 related pattern with RE2@Pd12Si6 forming the fcc substructure and the RE1@Pd16 polyhedra filling the tetrahedral voids. The silicon atoms have slightly distorted square antiprismatic palladium coordination (4 × 239 pm Si–Pd1 and 4 × 245 pm Si–Pd2). Temperature dependent magnetic susceptibility measurements of the Lu3Pd20Si6 sample indicate Pauli paramagnetism.