The chalcogenido indates K6In2Q6 (Q = S, Se, Te) were synthesized from melts of the pure elements at a maximum temperature of 700 °C. All three potassium salts contain dinuclear units [In2Q6]6– of two edge‐sharing [InQ4] tetrahedra. The sulfido and the selenido indate are isotypic and crystallize in the K6Mn2O6‐type structure [monoclinic, space group P21/c, a = 784.32(9)/809.32(3), b = 1274.58(14)/1322.37(4), c = 836.48(9)/870.53(3) pm, β = 97.900(2)/97.5877(8)°, Z = 2, R1 = 0.0123/0.0109; for Q = S/Se]. The tellurido indate K6In2Te6 crystallizes in a new orthorhombic structure type [space group Pnma, a = 1793.70(12), b = 1491.55(11), c = 837.40(6) pm, Z = 4, R1 = 0.0157]. In this structure, the telluride anions form a hexagonal close packing, in which K+ cations occupy all octahedral voids; the In3+ ions take 1/6 (but always adjacent) tetrahedral voids. This structure‐chemical relation to the h.c.p. packing, which is similarly found for most of the sodium dimetallates (e.g. Na6Fe2S6), is substantiated by a full crystallographic group‐subgroup tree. The crystal chemistry of the new indates is discussed and compared with that of alkali chalcogenido metallates(III) of Fe, Al and Ga containing [M2Q6]6– dimers, which overall form as many as ten different structure types. DFT band structure calculations of the three title compounds exhibit bandgaps, which continuously decrease from the S to the Te compound and which are also in accordance with the pale yellow (S), bright yellow (Se) and red‐brown (Te) color of the compounds. The chemical bonding in the salts and within the metallate anion is discussed on the basis of the partial DOS and a Bader analysis of the calculated electron density.

The new chalcogenido ortho indates(III) K 5 [InSe 4 ] and K 12 [InS 4 ] 2 (S) were synthesized from melts of the elements (Se) [or with S/In 2 S 3 as chalcogen source] at maximum temperatures of 700/ 800°C. The two potassium salts, which were characterized by means of X-ray single crystal structure analysis, contain isolated tetrahedral ortho anions [InQ 4 ] 5-. K 5 [InSe 4 ] crystallizes in a new structure type [monoclinic, space group C2/c, a = 2014.2(2), b = 1553.1(2), c = 1661.1(2) pm, β = 94.716(2)°, Z = 16, R 1 = 0.0317]. The complex structure contains two crystallographically different [InSe 4 ] 5tetrahedra [d(In•••Se) = 254.3-263.6 pm], which are arranged into 4 4 [In(1), A] and 3 2 .4.3.4 [In(2), B] nets. These nets are |:ABAЈBЈ:| stacked along the a axis. The 11 crystallographically independent K + ions are coordinated by four (1ϫ), five (3ϫ) and six (7ϫ) selenido anions [d(K-Se) = 309-415 pm]. The crystal structure and the calculated electronic structure of the pure ortho indate K 5 [InSe 4 ] are compared with the known "double salts" K 9 [InSe 4 ] 2 (Se) and K 9 [InSe 4 ](Se 2)(Se),