A new 3D rare-earth coordination polymer[Ce 2(H 2btc)(btc)(H 2O) 2] n (1) was hydrothermally synthesized and its structure was characterized by the single crystal X-ray diffraction. Compound 1 crystallizes in a triclinic crystal system,space group P 1 with a =0.641 17(13) nm, b = 0.939 41(19) nm , c =0.957 97(19) nm, α =103.888(17)°, β =74.57(3)°, γ =76.71(3)°, V = 0.540 98(19) nm 3 , Z=1,\{R=\}0.026 4,wR 2 =0.077 9. The three-dimensional compound 1 is built by linking one crystallographically independent nine-coordination Ce(Ⅲ) subunit through the btc and the H 2btc ligands. Each nine-coordinate Ce(Ⅲ) unit is a distorted tricapped trigonal prism,of which eight oxygen atoms belong to six different carboxylate groups of btc or H 2btc and a water molecule,with the Ce(Ⅲ)—O bond lengths ranging from 0.240 3(3) nm to 0.263 6(3) nm.
