Eu(GaAs)2 crystallizes in the monoclinic P2/m space group. There are three inequivalent Eu sites. In the first Eu site, Eu(1) is bonded to one As(1), one As(3), two equivalent As(2), and two equivalent As(4) atoms to form distorted EuAs6 octahedra that share corners with four equivalent Ga(2)GaAs3 tetrahedra, edges with two equivalent Eu(1)As6 octahedra, edges with two equivalent Eu(2)As6 octahedra, edges with two equivalent Eu(3)As6 octahedra, and edges with two equivalent Ga(1)GaAs3 tetrahedra. In the second Eu site, Eu(2) is bonded to two equivalent As(4) and four equivalent As(1) atoms to form EuAs6 octahedra that share corners with two equivalent Ga(1)GaAs3 tetrahedra, corners with four equivalent Ga(2)GaAs3 tetrahedra, edges with two equivalent Eu(2)As6 octahedra, edges with four equivalent Eu(1)As6 octahedra, and edges with two equivalent Ga(2)GaAs3 tetrahedra. In the third Eu site, Eu(3) is bonded to two equivalent As(2) and four equivalent As(3) atoms to form EuAs6 octahedra that share corners with two equivalent Ga(2)GaAs3 tetrahedra, corners with four equivalent Ga(1)GaAs3 tetrahedra, edges with two equivalent Eu(3)As6 octahedra, edges with four equivalent Eu(1)As6 octahedra, and edges with two equivalent Ga(1)GaAs3 tetrahedra. There are four inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one Ga(1), one As(4), and two equivalent As(3) atoms to form distorted GaGaAs3 tetrahedra that share  a cornercorner with one Eu(2)As6 octahedra,  a cornercorner with one As(4)Eu3Ga3 octahedra, corners with two equivalent Eu(3)As6 octahedra, corners with two equivalent As(3)Eu3Ga3 octahedra, corners with two equivalent Ga(1)GaAs3 tetrahedra,  an edgeedge with one Eu(3)As6 octahedra, and edges with two equivalent Eu(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 1-66°. In the second Ga site, Ga(2) is bonded to one Ga(2), one As(2), and two equivalent As(1) atoms to form distorted GaGaAs3 tetrahedra that share  a cornercorner with one Eu(3)As6 octahedra,  a cornercorner with one As(2)Eu3Ga3 octahedra, corners with two equivalent Eu(2)As6 octahedra, corners with two equivalent As(1)Eu3Ga3 octahedra, corners with four equivalent Eu(1)As6 octahedra, corners with two equivalent Ga(2)GaAs3 tetrahedra, and  an edgeedge with one Eu(2)As6 octahedra. The corner-sharing octahedral tilt angles range from 5-84°. In the third Ga site, Ga(3) is bonded in a 4-coordinate geometry to one Ga(4), one As(3), and two equivalent As(2) atoms. In the fourth Ga site, Ga(4) is bonded in a 4-coordinate geometry to one Ga(3), one As(1), and two equivalent As(4) atoms. There are four inequivalent As sites. In the first As site, As(1) is bonded to one Eu(1), two equivalent Eu(2), one Ga(4), and two equivalent Ga(2) atoms to form AsEu3Ga3 octahedra that share  a cornercorner with one As(3)Eu3Ga3 octahedra, corners with two equivalent As(1)Eu3Ga3 octahedra, corners with four equivalent As(2)Eu3Ga3 octahedra, corners with two equivalent Ga(2)GaAs3 tetrahedra, edges with three equivalent As(1)Eu3Ga3 octahedra, and edges with four equivalent As(4)Eu3Ga3 octahedra. The corner-sharing octahedral tilt angles range from 0-78°. In the second As site, As(2) is bonded to one Eu(3), two equivalent Eu(1), one Ga(2), and two equivalent Ga(3) atoms to form AsEu3Ga3 octahedra that share  a cornercorner with one As(2)Eu3Ga3 octahedra, corners with two equivalent As(4)Eu3Ga3 octahedra, corners with four equivalent As(1)Eu3Ga3 octahedra,  a cornercorner with one Ga(2)GaAs3 tetrahedra,  an edgeedge with one As(4)Eu3Ga3 octahedra, edges with two equivalent As(2)Eu3Ga3 octahedra, and edges with four equivalent As(3)Eu3Ga3 octahedra. The corner-sharing octahedral tilt angles range from 0-78°. In the third As site, As(3) is bonded to one Eu(1), two equivalent Eu(3), one Ga(3), and two equivalent Ga(1) atoms to form AsEu3Ga3 octahedra that share  a cornercorner with one As(1)Eu3Ga3 octahedra, corners with two equivalent As(3)Eu3Ga3 octahedra, corners with two equivalent Ga(1)GaAs3 tetrahedra, edges with two equivalent As(4)Eu3Ga3 octahedra, edges with three equivalent As(3)Eu3Ga3 octahedra, and edges with four equivalent As(2)Eu3Ga3 octahedra. The corner-sharing octahedral tilt angles range from 0-17°. In the fourth As site, As(4) is bonded to one Eu(2), two equivalent Eu(1), one Ga(1), and two equivalent Ga(4) atoms to form AsEu3Ga3 octahedra that share  a cornercorner with one As(4)Eu3Ga3 octahedra, corners with two equivalent As(2)Eu3Ga3 octahedra,  a cornercorner with one Ga(1)GaAs3 tetrahedra,  an edgeedge with one As(2)Eu3Ga3 octahedra, edges with two equivalent As(3)Eu3Ga3 octahedra, edges with two equivalent As(4)Eu3Ga3 octahedra, and edges with four equivalent As(1)Eu3Ga3 octahedra. The corner-sharing octahedral tilt angles range from 0-12°.
Eu(GaAs)2 crystallizes in the monoclinic P2/m space group. There are three inequivalent Eu sites. In the first Eu site, Eu(1) is bonded to one As(1), one As(3), two equivalent As(2), and two equivalent As(4) atoms to form distorted EuAs6 octahedra that share corners with four equivalent Ga(2)GaAs3 tetrahedra, edges with two equivalent Eu(1)As6 octahedra, edges with two equivalent Eu(2)As6 octahedra, edges with two equivalent Eu(3)As6 octahedra, and edges with two equivalent Ga(1)GaAs3 tetrahedra. The Eu(1)-As(1) bond length is 3.17 Å. The Eu(1)-As(3) bond length is 3.16 Å. Both Eu(1)-As(2) bond lengths are 3.11 Å. Both Eu(1)-As(4) bond lengths are 3.11 Å. In the second Eu site, Eu(2) is bonded to two equivalent As(4) and four equivalent As(1) atoms to form EuAs6 octahedra that share corners with two equivalent Ga(1)GaAs3 tetrahedra, corners with four equivalent Ga(2)GaAs3 tetrahedra, edges with two equivalent Eu(2)As6 octahedra, edges with four equivalent Eu(1)As6 octahedra, and edges with two equivalent Ga(2)GaAs3 tetrahedra. Both Eu(2)-As(4) bond lengths are 3.03 Å. All Eu(2)-As(1) bond lengths are 3.08 Å. In the third Eu site, Eu(3) is bonded to two equivalent As(2) and four equivalent As(3) atoms to form EuAs6 octahedra that share corners with two equivalent Ga(2)GaAs3 tetrahedra, corners with four equivalent Ga(1)GaAs3 tetrahedra, edges with two equivalent Eu(3)As6 octahedra, edges with four equivalent Eu(1)As6 octahedra, and edges with two equivalent Ga(1)GaAs3 tetrahedra. Both Eu(3)-As(2) bond lengths are 3.08 Å. All Eu(3)-As(3) bond lengths are 3.04 Å. There are four inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one Ga(1), one As(4), and two equivalent As(3) atoms to form distorted GaGaAs3 tetrahedra that share  a cornercorner with one Eu(2)As6 octahedra,  a cornercorner with one As(4)Eu3Ga3 octahedra, corners with two equivalent Eu(3)As6 octahedra, corners with two equivalent As(3)Eu3Ga3 octahedra, corners with two equivalent Ga(1)GaAs3 tetrahedra,  an edgeedge with one Eu(3)As6 octahedra, and edges with two equivalent Eu(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 1-66°. The Ga(1)-Ga(1) bond length is 2.45 Å. The Ga(1)-As(4) bond length is 2.51 Å. Both Ga(1)-As(3) bond lengths are 2.53 Å. In the second Ga site, Ga(2) is bonded to one Ga(2), one As(2), and two equivalent As(1) atoms to form distorted GaGaAs3 tetrahedra that share  a cornercorner with one Eu(3)As6 octahedra,  a cornercorner with one As(2)Eu3Ga3 octahedra, corners with two equivalent Eu(2)As6 octahedra, corners with two equivalent As(1)Eu3Ga3 octahedra, corners with four equivalent Eu(1)As6 octahedra, corners with two equivalent Ga(2)GaAs3 tetrahedra, and  an edgeedge with one Eu(2)As6 octahedra. The corner-sharing octahedral tilt angles range from 5-84°. The Ga(2)-Ga(2) bond length is 2.46 Å. The Ga(2)-As(2) bond length is 2.55 Å. Both Ga(2)-As(1) bond lengths are 2.54 Å. In the third Ga site, Ga(3) is bonded in a 4-coordinate geometry to one Ga(4), one As(3), and two equivalent As(2) atoms. The Ga(3)-Ga(4) bond length is 2.41 Å. The Ga(3)-As(3) bond length is 2.51 Å. Both Ga(3)-As(2) bond lengths are 2.54 Å. In the fourth Ga site, Ga(4) is bonded in a 4-coordinate geometry to one Ga(3), one As(1), and two equivalent As(4) atoms. The Ga(4)-As(1) bond length is 2.54 Å. Both Ga(4)-As(4) bond lengths are 2.52 Å. There are four inequivalent As sites. In the first As site, As(1) is bonded to one Eu(1), two equivalent Eu(2), one Ga(4), and two equivalent Ga(2) atoms to form AsEu3Ga3 octahedra that share  a cornercorner with one As(3)Eu3Ga3 octahedra, corners with two equivalent As(1)Eu3Ga3 octahedra, corners with four equivalent As(2)Eu3Ga3 octahedra, corners with two equivalent Ga(2)GaAs3 tetrahedra, edges with three equivalent As(1)Eu3Ga3 octahedra, and edges with four equivalent As(4)Eu3Ga3 octahedra. The corner-sharing octahedral tilt angles range from 0-78°. In the second As site, As(2) is bonded to one Eu(3), two equivalent Eu(1), one Ga(2), and two equivalent Ga(3) atoms to form AsEu3Ga3 octahedra that share  a cornercorner with one As(2)Eu3Ga3 octahedra, corners with two equivalent As(4)Eu3Ga3 octahedra, corners with four equivalent As(1)Eu3Ga3 octahedra,  a cornercorner with one Ga(2)GaAs3 tetrahedra,  an edgeedge with one As(4)Eu3Ga3 octahedra, edges with two equivalent As(2)Eu3Ga3 octahedra, and edges with four equivalent As(3)Eu3Ga3 octahedra. The corner-sharing octahedral tilt angles range from 0-78°. In the third As site, As(3) is bonded to one Eu(1), two equivalent Eu(3), one Ga(3), and two equivalent Ga(1) atoms to form AsEu3Ga3 octahedra that share  a cornercorner with one As(1)Eu3Ga3 octahedra, corners with two equivalent As(3)Eu3Ga3 octahedra, corners with two equivalent Ga(1)GaAs3 tetrahedra, edges with two equivalent As(4)Eu3Ga3 octahedra, edges with three equivalent As(3)Eu3Ga3 octahedra, and edges with four equivalent As(2)Eu3Ga3 octahedra. The corner-sharing octahedral tilt angles range from 0-17°. In the fourth As site, As(4) is bonded to one Eu(2), two equivalent Eu(1), one Ga(1), and two equivalent Ga(4) atoms to form AsEu3Ga3 octahedra that share  a cornercorner with one As(4)Eu3Ga3 octahedra, corners with two equivalent As(2)Eu3Ga3 octahedra,  a cornercorner with one Ga(1)GaAs3 tetrahedra,  an edgeedge with one As(2)Eu3Ga3 octahedra, edges with two equivalent As(3)Eu3Ga3 octahedra, edges with two equivalent As(4)Eu3Ga3 octahedra, and edges with four equivalent As(1)Eu3Ga3 octahedra. The corner-sharing octahedral tilt angles range from 0-12°.