Four complex intermetallic compounds BaAu6 Ga-x(6) (y) (x = 1, y = 0 9) (I), BaAu6 Al-x(6) (y) (x = 0 9, y = 0 6) (II), EuAu6 Ga-2(5) (8) (III), and EuAu6 Al-1(5) (9) (IV) have been synthesized, and their structures and homogeneity ranges have been determined by single crystal and powder X-ray diffraction Whereas I and II originate from the NaZn13-type structure (cF104-112, Fm (3) over barc), III (tP52, P4/nbm) is derived from the tetragonal Ce2Ni17Si9-type, and IV (oP104, Pbcm) crystallizes in a new orthorhombic structure type Both I and II feature formally anionic networks with completely mixed site occupation by Au and triel (Tr = Al, Ga) atoms, while a successive decrease of local symmetry from the parental structures of I and II to III and, ultimately, to IV correlates with increasing separation of Au and Tr on individual crystallographic sites Density functional theory-based calculations were employed to determine the crystallographic site preferences of Au and the respective triel element to elucidate reasons for the atom distribution (coloring scheme) Chemical bonding analyses for two different EuAu6Tr6 models reveal maximization of the number of heteroatomic AuTr bonds as the driving force for atom organization The Fermi levels fall in broad pseudogaps for both models allowing some electronic flexibility Spin-polarized band structure calculations on the EuAu6Tr6 models hint to singlet ground states for europium and long-range magnetic coupling for both EuAu6 Ga-2(5) (8) (III) and EuAu6 Al-1(5) (9) (IV) This is substantiated by experimental evidence because both compounds show nearly identical magnetic behavior with ferromagnetic transitions at T-C = 6 K and net magnetic moments of 7 35 mu(B)/f u at 2 K The effective moments of 8 3 mu(B)/f u , determined from Curie-Weiss fits, point to divalent oxidation states for europium in both III and IV