Variations modulo 4 – 4 + , 4 + 3 – 3 + 4 – , 4 – 5 + , 5 – 4 + 4 – 5 + 4 – 4 + with Rare Earth Carbide Halides

The new compounds Pr 8 (C 2 ) 4 Cl 5  (1), Pr 14 (C 2 ) 7 Cl 9  (2), Pr 22 (C 2 ) 11 Cl 14  (3), Ce 2 (C 2 )Cl (4), La 2 (C 2 )Br (5), Ce 2 (C 2 )Br (6), Pr 2 (C 2 )Br (7), Ce 18 (C 2 ) 9 Cl 11  (8), and Ce 26 (C 2 ) 13 Cl 16  (9) were prepared by heating mixtures of LnX 3 , Ln and carbon or in an alternatively way LnX 3 , and “ Ln 2 C 3– x ” in appropriate amounts for several days between 750 and 1200 °C. The crystal structures were investigated by X‐ray powder analysis (5–7) and/or single crystal diffraction (1–4, 8, 9). Pr 8 (C 2 ) 4 Cl 5 crystallizes in space group P 2 1 / c with the lattice parameters a = 7.6169(12), b = 16.689(2), c = 6.7688(2) Å, β = 103.94(1) °, Pr 14 (C 2 ) 7 Cl 9 in Pc with a = 7.6134(15), b = 29.432(6), c = 6.7705(14) Å, β = 104.00(3) °, Pr 22 (C 2 ) 11 Cl 14 in P 2 1 / c with a = 7.612(2), b = 46.127(9), c = 6.761(1) Å, β = 103.92(3) °, Ce 2 (C 2 ) 2 Cl in C 2/ c with a = 14.573(3), b = 4.129(1), c = 6.696(1) Å, β = 101.37(3) °, La 2 (C 2 ) 2 Br in C 2/ c with a = 15.313(5), b = 4.193(2), c = 6.842(2) Å, β = 100.53(3) °, Ce 2 (C 2 ) 2 Br in C 2/ c with a = 15.120(3), b = 4.179(1), c = 6.743(2) Å, β = 101.09(3) °, Pr 2 (C 2 ) 2 Br in C 2/ c with a = 15.054(5), b = 4.139(1), c = 6.713(3) Å, β = 101.08(3) °, Ce 18 (C 2 ) 9 Cl 11 in P $\bar{1}$ with a = 6.7705(14), b = 7.6573(15), c = 18.980(4) Å, α = 88.90(3) °, β = 80.32(3) °, γ = 76.09(3) °, and Ce 26 (C 2 ) 13 Cl 16 in P 2 1 / c with a = 7.6644(15), b = 54.249(11), c = 6.7956(14) Å, β = 103.98(3) ° The crystal structures are composed of Ln octahedra centered by C 2 dumbbells. Such Ln 6 (C 2 )‐octahedra are condensed into chains which are joined into undulated sheets. In compounds 1–4 three and four up and down inclined ribbons alternate (4 + 4 – , 4 + 3 – 3 + 4 –,  4 + 4 – 3 + 4 – 4 + 3 – ), in compounds 8 and 9 four and five (4 + 5 – , 5 + 4 – 4 + 5 – 4 + 4 – ), and in compounds 4–7 one, one ribbons (1 + 1 – ) are present. The Ln ‐(C 2 )‐ Ln layers are separated by monolayers of X atoms.