Syntheses and single-crystal structures of La3AgSnS7, Ln3MxMS7 (Ln = La, Ho, Er; M = Ge, Sn; 1/4 ≤ x ≤ 1/2)

In our investigation of non-centrosymmetric rare earth sulfides in the La3AgSnS7/KBr, LaAlGeS5/NaBr, HoAlGeS5/KBr, ErAlGeS5/NaBr, Er3AgGeS7/KBr and La3NaSnS7/NaBr systems, five compounds belonging to the R6B2C2Q14 family have been obtained. These compounds crystallize in the P63 space group, and the crystal data are as follows—La3AgSnS7: a = 10.3780(15) Å, c = 5.9900(12) Å, Z = 2; La3Ge0.25GeS7: a = 10.2970(15) Å, c = 5.8120(12) Å, Z = 2; Ho3Ge0.272(10)GeS7: a = 9.6480(14) Å, c = 5.7920(12) Å, Z = 2; Er3Ge0.330(10)GeS7: a = 9.5930(14) Å, c = 5.8490(12) Å, Z = 2; La3Sn0.25SnS7: a = 10.2770(15) Å, c = 6.0030(12) Å, Z = 2. Single-crystal analysis indicated that the crystal structures consist of three types of building block: LnSn, MS4, and AgS3 (for La3AgSnS7) or MS6 units (for Ln3MxMS7, Ln = La, Ho, Er; M = Ge, Sn; 1/4 ≤ x ≤ 1/2), as any other compounds belonging to the R6B2C2Q14 family. Ln3MxMS7 (Ln = La, Ho, Er; M = Ge, Sn; 1/4 ≤ x ≤ 1/2) are deficient compounds with the B sites occupied partly by M(II), and/or M(IV).