ZnAs2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to one As(2), one As(3), and two equivalent As(4) atoms to form ZnAs4 tetrahedra that share corners with two equivalent Zn(1)As4 tetrahedra, corners with two equivalent Zn(2)As4 tetrahedra, corners with two equivalent As(1)Zn2As2 tetrahedra, corners with two equivalent As(2)Zn2As2 tetrahedra, and corners with two equivalent As(4)Zn2As2 tetrahedra. In the second Zn site, Zn(2) is bonded to one As(2), one As(3), and two equivalent As(1) atoms to form ZnAs4 tetrahedra that share corners with two equivalent Zn(1)As4 tetrahedra, corners with two equivalent Zn(2)As4 tetrahedra, corners with two equivalent As(1)Zn2As2 tetrahedra, corners with two equivalent As(2)Zn2As2 tetrahedra, and corners with two equivalent As(4)Zn2As2 tetrahedra. There are four inequivalent As sites. In the first As site, As(1) is bonded to two equivalent Zn(2), one As(2), and one As(3) atom to form distorted AsZn2As2 tetrahedra that share corners with two equivalent Zn(1)As4 tetrahedra, corners with two equivalent Zn(2)As4 tetrahedra, corners with two equivalent As(1)Zn2As2 tetrahedra, corners with two equivalent As(2)Zn2As2 tetrahedra, and corners with two equivalent As(4)Zn2As2 tetrahedra. In the second As site, As(2) is bonded to one Zn(1), one Zn(2), one As(1), and one As(4) atom to form distorted AsZn2As2 tetrahedra that share corners with two equivalent Zn(1)As4 tetrahedra, corners with two equivalent Zn(2)As4 tetrahedra, corners with two equivalent As(1)Zn2As2 tetrahedra, and corners with two equivalent As(4)Zn2As2 tetrahedra. In the third As site, As(3) is bonded in a 4-coordinate geometry to one Zn(1), one Zn(2), one As(1), and one As(4) atom. In the fourth As site, As(4) is bonded to two equivalent Zn(1), one As(2), and one As(3) atom to form distorted AsZn2As2 tetrahedra that share corners with two equivalent Zn(1)As4 tetrahedra, corners with two equivalent Zn(2)As4 tetrahedra, corners with two equivalent As(1)Zn2As2 tetrahedra, corners with two equivalent As(2)Zn2As2 tetrahedra, and corners with two equivalent As(4)Zn2As2 tetrahedra.
ZnAs2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to one As(2), one As(3), and two equivalent As(4) atoms to form ZnAs4 tetrahedra that share corners with two equivalent Zn(1)As4 tetrahedra, corners with two equivalent Zn(2)As4 tetrahedra, corners with two equivalent As(1)Zn2As2 tetrahedra, corners with two equivalent As(2)Zn2As2 tetrahedra, and corners with two equivalent As(4)Zn2As2 tetrahedra. The Zn(1)-As(2) bond length is 2.47 Å. The Zn(1)-As(3) bond length is 2.47 Å. There is one shorter (2.41 Å) and one longer (2.42 Å) Zn(1)-As(4) bond length. In the second Zn site, Zn(2) is bonded to one As(2), one As(3), and two equivalent As(1) atoms to form ZnAs4 tetrahedra that share corners with two equivalent Zn(1)As4 tetrahedra, corners with two equivalent Zn(2)As4 tetrahedra, corners with two equivalent As(1)Zn2As2 tetrahedra, corners with two equivalent As(2)Zn2As2 tetrahedra, and corners with two equivalent As(4)Zn2As2 tetrahedra. The Zn(2)-As(2) bond length is 2.51 Å. The Zn(2)-As(3) bond length is 2.50 Å. There is one shorter (2.45 Å) and one longer (2.49 Å) Zn(2)-As(1) bond length. There are four inequivalent As sites. In the first As site, As(1) is bonded to two equivalent Zn(2), one As(2), and one As(3) atom to form distorted AsZn2As2 tetrahedra that share corners with two equivalent Zn(1)As4 tetrahedra, corners with two equivalent Zn(2)As4 tetrahedra, corners with two equivalent As(1)Zn2As2 tetrahedra, corners with two equivalent As(2)Zn2As2 tetrahedra, and corners with two equivalent As(4)Zn2As2 tetrahedra. The As(1)-As(2) bond length is 2.46 Å. The As(1)-As(3) bond length is 2.45 Å. In the second As site, As(2) is bonded to one Zn(1), one Zn(2), one As(1), and one As(4) atom to form distorted AsZn2As2 tetrahedra that share corners with two equivalent Zn(1)As4 tetrahedra, corners with two equivalent Zn(2)As4 tetrahedra, corners with two equivalent As(1)Zn2As2 tetrahedra, and corners with two equivalent As(4)Zn2As2 tetrahedra. The As(2)-As(4) bond length is 2.43 Å. In the third As site, As(3) is bonded in a 4-coordinate geometry to one Zn(1), one Zn(2), one As(1), and one As(4) atom. The As(3)-As(4) bond length is 2.42 Å. In the fourth As site, As(4) is bonded to two equivalent Zn(1), one As(2), and one As(3) atom to form distorted AsZn2As2 tetrahedra that share corners with two equivalent Zn(1)As4 tetrahedra, corners with two equivalent Zn(2)As4 tetrahedra, corners with two equivalent As(1)Zn2As2 tetrahedra, corners with two equivalent As(2)Zn2As2 tetrahedra, and corners with two equivalent As(4)Zn2As2 tetrahedra.