CsEr2Cl7 crystallizes in the orthorhombic Pnma space group. Cs(1) is bonded in a 10-coordinate geometry to two equivalent Cl(1), two equivalent Cl(2), two equivalent Cl(4), and four equivalent Cl(3) atoms. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one Cl(4), two equivalent Cl(1), two equivalent Cl(2), and two equivalent Cl(3) atoms to form a mixture of distorted face and edge-sharing ErCl7 pentagonal bipyramids. In the second Er site, Er(2) is bonded to one Cl(4), two equivalent Cl(1), two equivalent Cl(2), and two equivalent Cl(3) atoms to form a mixture of distorted face and edge-sharing ErCl7 pentagonal bipyramids. There are four inequivalent Cl sites. In the first Cl site, Cl(4) is bonded to two equivalent Cs(1), one Er(1), and one Er(2) atom to form a mixture of distorted corner and edge-sharing ClCs2Er2 trigonal pyramids. In the second Cl site, Cl(1) is bonded in a distorted L-shaped geometry to one Cs(1), one Er(1), and one Er(2) atom. In the third Cl site, Cl(2) is bonded in a distorted trigonal non-coplanar geometry to one Cs(1), one Er(1), and one Er(2) atom. In the fourth Cl site, Cl(3) is bonded to two equivalent Cs(1), one Er(1), and one Er(2) atom to form a mixture of distorted corner and edge-sharing ClCs2Er2 tetrahedra.
CsEr2Cl7 crystallizes in the orthorhombic Pnma space group. Cs(1) is bonded in a 10-coordinate geometry to two equivalent Cl(1), two equivalent Cl(2), two equivalent Cl(4), and four equivalent Cl(3) atoms. Both Cs(1)-Cl(1) bond lengths are 3.71 Å. Both Cs(1)-Cl(2) bond lengths are 3.54 Å. Both Cs(1)-Cl(4) bond lengths are 3.60 Å. There are two shorter (3.60 Å) and two longer (3.65 Å) Cs(1)-Cl(3) bond lengths. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one Cl(4), two equivalent Cl(1), two equivalent Cl(2), and two equivalent Cl(3) atoms to form a mixture of distorted face and edge-sharing ErCl7 pentagonal bipyramids. The Er(1)-Cl(4) bond length is 2.75 Å. Both Er(1)-Cl(1) bond lengths are 2.67 Å. Both Er(1)-Cl(2) bond lengths are 2.69 Å. Both Er(1)-Cl(3) bond lengths are 2.67 Å. In the second Er site, Er(2) is bonded to one Cl(4), two equivalent Cl(1), two equivalent Cl(2), and two equivalent Cl(3) atoms to form a mixture of distorted face and edge-sharing ErCl7 pentagonal bipyramids. The Er(2)-Cl(4) bond length is 2.71 Å. Both Er(2)-Cl(1) bond lengths are 2.69 Å. Both Er(2)-Cl(2) bond lengths are 2.66 Å. Both Er(2)-Cl(3) bond lengths are 2.71 Å. There are four inequivalent Cl sites. In the first Cl site, Cl(4) is bonded to two equivalent Cs(1), one Er(1), and one Er(2) atom to form a mixture of distorted corner and edge-sharing ClCs2Er2 trigonal pyramids. In the second Cl site, Cl(1) is bonded in a distorted L-shaped geometry to one Cs(1), one Er(1), and one Er(2) atom. In the third Cl site, Cl(2) is bonded in a distorted trigonal non-coplanar geometry to one Cs(1), one Er(1), and one Er(2) atom. In the fourth Cl site, Cl(3) is bonded to two equivalent Cs(1), one Er(1), and one Er(2) atom to form a mixture of distorted corner and edge-sharing ClCs2Er2 tetrahedra.