TmCd2 crystallizes in the trigonal P-3m1 space group. Tm(1) is bonded to two equivalent Tm(1) and six equivalent Cd(1) atoms to form TmTm2Cd6 hexagonal bipyramids that share corners with two equivalent Tm(1)Tm2Cd6 hexagonal bipyramids, corners with six equivalent Cd(1)Tm3Cd5 hexagonal bipyramids, edges with six equivalent Tm(1)Tm2Cd6 hexagonal bipyramids, and edges with eighteen equivalent Cd(1)Tm3Cd5 hexagonal bipyramids. Cd(1) is bonded to three equivalent Tm(1) and five equivalent Cd(1) atoms to form distorted CdTm3Cd5 hexagonal bipyramids that share corners with three equivalent Tm(1)Tm2Cd6 hexagonal bipyramids, corners with five equivalent Cd(1)Tm3Cd5 hexagonal bipyramids, edges with nine equivalent Tm(1)Tm2Cd6 hexagonal bipyramids, and edges with fifteen equivalent Cd(1)Tm3Cd5 hexagonal bipyramids.
TmCd2 crystallizes in the trigonal P-3m1 space group. Tm(1) is bonded to two equivalent Tm(1) and six equivalent Cd(1) atoms to form TmTm2Cd6 hexagonal bipyramids that share corners with two equivalent Tm(1)Tm2Cd6 hexagonal bipyramids, corners with six equivalent Cd(1)Tm3Cd5 hexagonal bipyramids, edges with six equivalent Tm(1)Tm2Cd6 hexagonal bipyramids, and edges with eighteen equivalent Cd(1)Tm3Cd5 hexagonal bipyramids. Both Tm(1)-Tm(1) bond lengths are 3.20 Å. All Tm(1)-Cd(1) bond lengths are 3.12 Å. Cd(1) is bonded to three equivalent Tm(1) and five equivalent Cd(1) atoms to form distorted CdTm3Cd5 hexagonal bipyramids that share corners with three equivalent Tm(1)Tm2Cd6 hexagonal bipyramids, corners with five equivalent Cd(1)Tm3Cd5 hexagonal bipyramids, edges with nine equivalent Tm(1)Tm2Cd6 hexagonal bipyramids, and edges with fifteen equivalent Cd(1)Tm3Cd5 hexagonal bipyramids. There are three shorter (3.14 Å) and two longer (3.20 Å) Cd(1)-Cd(1) bond lengths.