The new compounds Pr8(C2)4Cl5 (1), Pr14(C2)7Cl9 (2), Pr 22(C2)11Cl14 (3), Ce 2(C2)Cl (4), La2(C2)Br (5), Ce 2(C2)Br (6), Pr2(C2)Br (7), Ce 18(C2)9Cl11 (8), and Ce 26(C2)13Cl16 (9) were prepared by heating mixtures of LnX3, Ln and carbon or in an alternatively way LnX3, and Ln2C3-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). Pr8(C2)4Cl5 crystallizes in space group P21/c with the lattice parameters a = 7.6169(12), b = 16.689(2), c = 6.7688(2) A, β = 103.94(1) °, Pr14(C2)7Cl9 in Pc with a = 7.6134(15), b = 29.432(6), c = 6.7705(14) A, β = 104.00(3) °, Pr22(C2)11Cl14 in P21/c with a = 7.612(2), b = 46.127(9), c = 6.761(1) A, β = 103.92(3) °, Ce2(C2)2Cl in C2/c with a = 14.573(3), b = 4.129(1), c = 6.696(1) A, β = 101.37(3) °, La 2(C2)2Br in C2/c with a = 15.313(5), b = 4.193(2), c = 6.842(2) A, β = 100.53(3) °, Ce2(C 2)2Br in C2/c with a = 15.120(3), b = 4.179(1), c = 6.743(2) A, β = 101.09(3) °, Pr2(C2) 2Br in C2/c with a = 15.054(5), b = 4.139(1), c = 6.713(3) A, β = 101.08(3) °, Ce18(C2)9Cl 11 in Pβar{1}$ with a = 6.7705(14), b = 7.6573(15), c = 18.980(4) A,α = 88.90(3) °, β = 80.32(3) °, γ = 76.09(3) °, and Ce26(C2)13Cl16 in P21/c with a = 7.6644(15), b = 54.249(11), c = 6.7956(14) A, β = 103.98(3) ° The crystal structures are composed of Ln octahedra centered by C2 dumbbells. Such Ln6(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-(C2)-Ln layers are separated by monolayers of X atoms. Copyright