CoNiAs4 is Marcasite-derived structured and crystallizes in the monoclinic P2/m space group. Co(1) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form CoAs6 octahedra that share corners with eight equivalent Ni(1)As6 octahedra, corners with two equivalent As(1)CoNi2As tetrahedra, corners with four equivalent As(2)Co2NiAs tetrahedra, and edges with two equivalent Co(1)As6 octahedra. The corner-sharing octahedral tilt angles are 56°. Ni(1) is bonded to two equivalent As(2) and four equivalent As(1) atoms to form NiAs6 octahedra that share corners with eight equivalent Co(1)As6 octahedra, corners with two equivalent As(2)Co2NiAs tetrahedra, corners with four equivalent As(1)CoNi2As tetrahedra, and edges with two equivalent Ni(1)As6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are two inequivalent As sites. In the first As site, As(1) is bonded to one Co(1), two equivalent Ni(1), and one As(1) atom to form distorted AsCoNi2As tetrahedra that share  a cornercorner with one Co(1)As6 octahedra, corners with two equivalent Ni(1)As6 octahedra, corners with five equivalent As(1)CoNi2As tetrahedra, corners with eight equivalent As(2)Co2NiAs tetrahedra, and  an edgeedge with one As(1)CoNi2As tetrahedra. The corner-sharing octahedral tilt angles are 74°. In the second As site, As(2) is bonded to two equivalent Co(1), one Ni(1), and one As(2) atom to form distorted AsCo2NiAs tetrahedra that share  a cornercorner with one Ni(1)As6 octahedra, corners with two equivalent Co(1)As6 octahedra, corners with five equivalent As(2)Co2NiAs tetrahedra, corners with eight equivalent As(1)CoNi2As tetrahedra, and  an edgeedge with one As(2)Co2NiAs tetrahedra. The corner-sharing octahedral tilt angles range from 73-77°.
CoNiAs4 is Marcasite-derived structured and crystallizes in the monoclinic P2/m space group. Co(1) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form CoAs6 octahedra that share corners with eight equivalent Ni(1)As6 octahedra, corners with two equivalent As(1)CoNi2As tetrahedra, corners with four equivalent As(2)Co2NiAs tetrahedra, and edges with two equivalent Co(1)As6 octahedra. The corner-sharing octahedral tilt angles are 56°. Both Co(1)-As(1) bond lengths are 2.33 Å. All Co(1)-As(2) bond lengths are 2.37 Å. Ni(1) is bonded to two equivalent As(2) and four equivalent As(1) atoms to form NiAs6 octahedra that share corners with eight equivalent Co(1)As6 octahedra, corners with two equivalent As(2)Co2NiAs tetrahedra, corners with four equivalent As(1)CoNi2As tetrahedra, and edges with two equivalent Ni(1)As6 octahedra. The corner-sharing octahedral tilt angles are 56°. Both Ni(1)-As(2) bond lengths are 2.38 Å. All Ni(1)-As(1) bond lengths are 2.40 Å. There are two inequivalent As sites. In the first As site, As(1) is bonded to one Co(1), two equivalent Ni(1), and one As(1) atom to form distorted AsCoNi2As tetrahedra that share  a cornercorner with one Co(1)As6 octahedra, corners with two equivalent Ni(1)As6 octahedra, corners with five equivalent As(1)CoNi2As tetrahedra, corners with eight equivalent As(2)Co2NiAs tetrahedra, and  an edgeedge with one As(1)CoNi2As tetrahedra. The corner-sharing octahedral tilt angles are 74°. The As(1)-As(1) bond length is 2.50 Å. In the second As site, As(2) is bonded to two equivalent Co(1), one Ni(1), and one As(2) atom to form distorted AsCo2NiAs tetrahedra that share  a cornercorner with one Ni(1)As6 octahedra, corners with two equivalent Co(1)As6 octahedra, corners with five equivalent As(2)Co2NiAs tetrahedra, corners with eight equivalent As(1)CoNi2As tetrahedra, and  an edgeedge with one As(2)Co2NiAs tetrahedra. The corner-sharing octahedral tilt angles range from 73-77°. The As(2)-As(2) bond length is 2.49 Å.