EuAs crystallizes in the monoclinic Pm space group. There are six inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 6-coordinate geometry to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. In the second Eu site, Eu(2) is bonded in a 6-coordinate geometry to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. In the third Eu site, Eu(3) is bonded in a 6-coordinate geometry to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. In the fourth Eu site, Eu(4) is bonded in a 6-coordinate geometry to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. In the fifth Eu site, Eu(5) is bonded in a 6-coordinate geometry to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. In the sixth Eu site, Eu(6) is bonded in a 6-coordinate geometry to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 7-coordinate geometry to one Eu(1), one Eu(2), one Eu(3), one Eu(4), one Eu(5), one Eu(6), and one As(1) atom. In the second As site, As(2) is bonded to one Eu(1), one Eu(2), one Eu(3), one Eu(4), one Eu(5), and one Eu(6) atom to form distorted AsEu6 octahedra that share corners with six equivalent As(3)Eu6As octahedra, edges with three equivalent As(3)Eu6As octahedra, and faces with two equivalent As(2)Eu6 octahedra. The corner-sharing octahedral tilt angles range from 44-56°. In the third As site, As(3) is bonded to one Eu(1), one Eu(2), one Eu(3), one Eu(4), one Eu(5), one Eu(6), and one As(3) atom to form distorted AsEu6As octahedra that share corners with six equivalent As(2)Eu6 octahedra, edges with three equivalent As(2)Eu6 octahedra, and faces with two equivalent As(3)Eu6As octahedra. The corner-sharing octahedral tilt angles range from 44-56°.
EuAs crystallizes in the monoclinic Pm space group. There are six inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 6-coordinate geometry to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. Both Eu(1)-As(1) bond lengths are 3.13 Å. Both Eu(1)-As(2) bond lengths are 3.06 Å. Both Eu(1)-As(3) bond lengths are 3.06 Å. In the second Eu site, Eu(2) is bonded in a 6-coordinate geometry to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. Both Eu(2)-As(1) bond lengths are 3.13 Å. Both Eu(2)-As(2) bond lengths are 3.07 Å. Both Eu(2)-As(3) bond lengths are 3.06 Å. In the third Eu site, Eu(3) is bonded in a 6-coordinate geometry to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. Both Eu(3)-As(1) bond lengths are 3.13 Å. Both Eu(3)-As(2) bond lengths are 3.06 Å. Both Eu(3)-As(3) bond lengths are 3.06 Å. In the fourth Eu site, Eu(4) is bonded in a 6-coordinate geometry to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. Both Eu(4)-As(1) bond lengths are 3.09 Å. Both Eu(4)-As(2) bond lengths are 3.08 Å. Both Eu(4)-As(3) bond lengths are 3.08 Å. In the fifth Eu site, Eu(5) is bonded in a 6-coordinate geometry to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. Both Eu(5)-As(1) bond lengths are 3.08 Å. Both Eu(5)-As(2) bond lengths are 3.08 Å. Both Eu(5)-As(3) bond lengths are 3.09 Å. In the sixth Eu site, Eu(6) is bonded in a 6-coordinate geometry to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. Both Eu(6)-As(1) bond lengths are 3.09 Å. Both Eu(6)-As(2) bond lengths are 3.08 Å. Both Eu(6)-As(3) bond lengths are 3.08 Å. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 7-coordinate geometry to one Eu(1), one Eu(2), one Eu(3), one Eu(4), one Eu(5), one Eu(6), and one As(1) atom. The As(1)-As(1) bond length is 2.61 Å. In the second As site, As(2) is bonded to one Eu(1), one Eu(2), one Eu(3), one Eu(4), one Eu(5), and one Eu(6) atom to form distorted AsEu6 octahedra that share corners with six equivalent As(3)Eu6As octahedra, edges with three equivalent As(3)Eu6As octahedra, and faces with two equivalent As(2)Eu6 octahedra. The corner-sharing octahedral tilt angles range from 44-56°. In the third As site, As(3) is bonded to one Eu(1), one Eu(2), one Eu(3), one Eu(4), one Eu(5), one Eu(6), and one As(3) atom to form distorted AsEu6As octahedra that share corners with six equivalent As(2)Eu6 octahedra, edges with three equivalent As(2)Eu6 octahedra, and faces with two equivalent As(3)Eu6As octahedra. The corner-sharing octahedral tilt angles range from 44-56°. The As(3)-As(3) bond length is 2.86 Å.