Er2Ni12As7 crystallizes in the hexagonal P-6 space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 15-coordinate geometry to three equivalent Ni(3), six equivalent Ni(1), and six equivalent As(2) atoms. In the second Er site, Er(2) is bonded in a 18-coordinate geometry to three equivalent Ni(1), three equivalent Ni(2), six equivalent Ni(3), and six equivalent As(3) atoms. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 4-coordinate geometry to one Er(2), two equivalent Er(1), two equivalent As(2), and two equivalent As(3) atoms. In the second Ni site, Ni(2) is bonded to one Er(2), one As(1), one As(2), and two equivalent As(3) atoms to form distorted NiErAs4 tetrahedra that share corners with two equivalent Ni(3)Er3As4 tetrahedra, corners with six equivalent Ni(2)ErAs4 tetrahedra, edges with two equivalent Ni(3)Er3As4 tetrahedra, and faces with two equivalent Ni(3)Er3As4 tetrahedra. In the third Ni site, Ni(3) is bonded to one Er(1), two equivalent Er(2), two equivalent As(2), and two equivalent As(3) atoms to form distorted NiEr3As4 tetrahedra that share corners with two equivalent Ni(2)ErAs4 tetrahedra, corners with six equivalent Ni(3)Er3As4 tetrahedra, edges with two equivalent Ni(3)Er3As4 tetrahedra, edges with two equivalent Ni(2)ErAs4 tetrahedra, faces with two equivalent Ni(3)Er3As4 tetrahedra, and faces with two equivalent Ni(2)ErAs4 tetrahedra. In the fourth Ni site, Ni(4) is bonded in a 5-coordinate geometry to one As(3), two equivalent As(1), and two equivalent As(2) atoms. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 9-coordinate geometry to three equivalent Ni(2) and six equivalent Ni(4) atoms. In the second As site, As(2) is bonded in a 9-coordinate geometry to two equivalent Er(1), one Ni(2), two equivalent Ni(1), two equivalent Ni(3), and two equivalent Ni(4) atoms. In the third As site, As(3) is bonded in a 9-coordinate geometry to two equivalent Er(2), one Ni(4), two equivalent Ni(1), two equivalent Ni(2), and two equivalent Ni(3) atoms.
Er2Ni12As7 crystallizes in the hexagonal P-6 space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 15-coordinate geometry to three equivalent Ni(3), six equivalent Ni(1), and six equivalent As(2) atoms. All Er(1)-Ni(3) bond lengths are 3.21 Å. All Er(1)-Ni(1) bond lengths are 3.03 Å. All Er(1)-As(2) bond lengths are 2.94 Å. In the second Er site, Er(2) is bonded in a 18-coordinate geometry to three equivalent Ni(1), three equivalent Ni(2), six equivalent Ni(3), and six equivalent As(3) atoms. All Er(2)-Ni(1) bond lengths are 3.26 Å. All Er(2)-Ni(2) bond lengths are 3.11 Å. All Er(2)-Ni(3) bond lengths are 3.10 Å. All Er(2)-As(3) bond lengths are 2.94 Å. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 4-coordinate geometry to one Er(2), two equivalent Er(1), two equivalent As(2), and two equivalent As(3) atoms. There is one shorter (2.30 Å) and one longer (2.32 Å) Ni(1)-As(2) bond length. Both Ni(1)-As(3) bond lengths are 2.38 Å. In the second Ni site, Ni(2) is bonded to one Er(2), one As(1), one As(2), and two equivalent As(3) atoms to form distorted NiErAs4 tetrahedra that share corners with two equivalent Ni(3)Er3As4 tetrahedra, corners with six equivalent Ni(2)ErAs4 tetrahedra, edges with two equivalent Ni(3)Er3As4 tetrahedra, and faces with two equivalent Ni(3)Er3As4 tetrahedra. The Ni(2)-As(1) bond length is 2.25 Å. The Ni(2)-As(2) bond length is 2.31 Å. Both Ni(2)-As(3) bond lengths are 2.37 Å. In the third Ni site, Ni(3) is bonded to one Er(1), two equivalent Er(2), two equivalent As(2), and two equivalent As(3) atoms to form distorted NiEr3As4 tetrahedra that share corners with two equivalent Ni(2)ErAs4 tetrahedra, corners with six equivalent Ni(3)Er3As4 tetrahedra, edges with two equivalent Ni(3)Er3As4 tetrahedra, edges with two equivalent Ni(2)ErAs4 tetrahedra, faces with two equivalent Ni(3)Er3As4 tetrahedra, and faces with two equivalent Ni(2)ErAs4 tetrahedra. Both Ni(3)-As(2) bond lengths are 2.37 Å. There is one shorter (2.33 Å) and one longer (2.39 Å) Ni(3)-As(3) bond length. In the fourth Ni site, Ni(4) is bonded in a 5-coordinate geometry to one As(3), two equivalent As(1), and two equivalent As(2) atoms. The Ni(4)-As(3) bond length is 2.41 Å. Both Ni(4)-As(1) bond lengths are 2.54 Å. Both Ni(4)-As(2) bond lengths are 2.61 Å. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 9-coordinate geometry to three equivalent Ni(2) and six equivalent Ni(4) atoms. In the second As site, As(2) is bonded in a 9-coordinate geometry to two equivalent Er(1), one Ni(2), two equivalent Ni(1), two equivalent Ni(3), and two equivalent Ni(4) atoms. In the third As site, As(3) is bonded in a 9-coordinate geometry to two equivalent Er(2), one Ni(4), two equivalent Ni(1), two equivalent Ni(2), and two equivalent Ni(3) atoms.