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The six isotypic alkali ortho chalcogenido manganates  A  6 [Mn II  Q  4 ] ( A =Rb, Cs;  Q =S, Se, Te) were synthesized – in most cases in pure phase – from stoichiometric mixtures of the manganese monochalcogenides Mn Q , the elemental chalcogens and Rb 2 S/Cs 2 S 2  (sulfido salts) or the pure alkali elements (selenido and tellurido salts) as alkali sources at maximum temperatures between 650 and 800°C. Their hexagonal crystal structures were refined by means of X-ray single crystal data (space group  P 6 3  mc , Na 6 ZnO 4 -type structure,  Z =2;  A / Q : Rb/S:  a =1019.34(2),  c =792.560(10) pm,  R 1=0.0166; Rb/Se:  a =1055.74(2),  c =821.14(2) pm,  R 1=0.0275; Rb/Te:  a =1126.68(2),  c =860.54(2) pm,  R 1=0.0152; Cs/S:  a =1056.68(2),  c =831.22(2) pm,  R 1=0.0168; Cs/Se:  a =1096.04(3),  c =858.13(2) pm,  R 1=0.0194; and Cs/Te:  a =1167.72(3),  c =896.95(2) pm,  R 1=0.0140). The chiral structures contain isolated  C  3  symmetric, but very close to ideal tetrahedral, ortho manganate(II) anions [Mn II  Q  4 ] 6−  with Mn– Q  distances of 248.7–250.7 ( Q =S), 260.7–263.0 ( Q =Se) and 280.0–282.4 pm ( Q =Te). The chalcogenide ions form a hexagonal closed packing with slightly puckered 3 6  nets, in which the  A (2) cations occupy 3/4 of the octahedral interstices, whereas Mn takes 1/8 and  A (1) 3/8 of the tetrahedral voids. Magnetic measurements on the three Cs compounds showed Curie-Weiss behavior down to a temperature of 1.9 K, with magnetic moments significantly reduced with respect to the expected spin-only value of a  d  5  ion. The electronic band structures of the four salts (Na/Rb) 6 Mn(S/Te) 4 , which were calculated within the GGA+ U  approach, allow a comparison of the chemical bonding characteristics and the magnetic properties within the alkali cation and the chalcogenido ligand series.

Alkali chalcogenido ortho manganates(II) A 6 Mn Q 4 ( A =Rb, Cs; Q =S, Se, Te)