In the shandite type solid solution InxSn2–xCo3S2 the transition from half metal ferromagnetic Sn2Co3S2 to the new thermoelectric InSnCo3S2 is related to A = In, Sn on different crystallographic sites. Effects and origin of crystal and electronic structure changes induced by A = In are now investigated within the solid solution 0 ≤ x ≤ 2 including In2Co3S2. Effects are studied from X‐ray data, 119Sn Mößbauer spectroscopy, and ab initio calculations. Their origin is explored by DFT modeling on site preference of In and Sn in a supercell, electric field gradients (EFG), spin polarization, band structures, and direct space analyses (ELF, AIM). Indium is found to cause the crystal structure distortion on one A site, the electronic structure distortion to the other, as a consequence of inverted anisotropic bonding.

The half metal (HFM) Sn2Co3S2 shows a fascinating S = 1/2 magnetism. Anisotropic coupling of spins in and between Co Kagomé layers by Sn sites is now studied from the substitution effects of S by Se by systematic and local experimental and first principles data. Trends in crystal structure changes (c/a ratio) as retrieved from XRD data on the solid solution Sn2Co3S2-xSex are complemented by DFT modelling on Sn2Co3SeS and hitherto unknown Sn2Co3Se2. The relationship of crystal structure effects with changes in Curie temperatures and magnetic hysteresis is shown from susceptibility measurements. An insight into the role of the Sn sites in magnetism and bonding is gained from (119)Sn Mössbauer spectroscopic measurements. Isomer shifts, quadrupole splitting, and magnetic hyperfine fields are interpreted by DFT calculations on chemical bonding, electric field gradients (EFG), Fermi contact, and spin polarization.

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The crystal and electronic structures of ordered half antiperovskites A2Rh3S2 = ARh3/2S (A = In, Sn, Tl, Pb, Bi) are investigated. From powder and single crystal data superstructures, rhodium site ordering, trends in bonding and coordination are analysed with respect to the A site atom. Comparisons address isotypic and isoelectronic relations to monoclinic parkerite (Bi2Ni3S2) type superconductors, the trigonal half‐metal ferromagnet Sn2Co3S2, and rhodium‐containing antiperovskites. Local structure and bonding is analysed with respect to the ordered occupation of half of S2A4 sites (= perovskite oxygen sites) and interlinking to 2D networks [Rh3S2]∞δ– by face‐, edge‐ and corner‐sharing. The theoretical part includes DFT band structure and ELF calculations, systematic comparisons to rhodium and antiperovskites, as well as spin‐polarised calculations on Sn2Rh3S2 and Pb2Rh3S2.