RhAs2 crystallizes in the monoclinic P2_1/c space group. Rh(1) is bonded to three equivalent As(1) and three equivalent As(2) atoms to form RhAs6 octahedra that share corners with eight equivalent Rh(1)As6 octahedra, corners with three equivalent As(1)AsRh3 tetrahedra, corners with three equivalent As(2)AsRh3 tetrahedra, and edges with two equivalent Rh(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 54-59°. There are two inequivalent As sites. In the first As site, As(1) is bonded to three equivalent Rh(1) and one As(2) atom to form AsAsRh3 tetrahedra that share corners with three equivalent Rh(1)As6 octahedra, corners with four equivalent As(1)AsRh3 tetrahedra, corners with nine equivalent As(2)AsRh3 tetrahedra, and  an edgeedge with one As(1)AsRh3 tetrahedra. The corner-sharing octahedral tilt angles range from 68-72°. In the second As site, As(2) is bonded to three equivalent Rh(1) and one As(1) atom to form distorted AsAsRh3 tetrahedra that share corners with three equivalent Rh(1)As6 octahedra, corners with four equivalent As(2)AsRh3 tetrahedra, corners with nine equivalent As(1)AsRh3 tetrahedra, and  an edgeedge with one As(2)AsRh3 tetrahedra. The corner-sharing octahedral tilt angles range from 73-78°.
RhAs2 crystallizes in the monoclinic P2_1/c space group. Rh(1) is bonded to three equivalent As(1) and three equivalent As(2) atoms to form RhAs6 octahedra that share corners with eight equivalent Rh(1)As6 octahedra, corners with three equivalent As(1)AsRh3 tetrahedra, corners with three equivalent As(2)AsRh3 tetrahedra, and edges with two equivalent Rh(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 54-59°. There are a spread of Rh(1)-As(1) bond distances ranging from 2.49-2.52 Å. There are a spread of Rh(1)-As(2) bond distances ranging from 2.42-2.44 Å. There are two inequivalent As sites. In the first As site, As(1) is bonded to three equivalent Rh(1) and one As(2) atom to form AsAsRh3 tetrahedra that share corners with three equivalent Rh(1)As6 octahedra, corners with four equivalent As(1)AsRh3 tetrahedra, corners with nine equivalent As(2)AsRh3 tetrahedra, and  an edgeedge with one As(1)AsRh3 tetrahedra. The corner-sharing octahedral tilt angles range from 68-72°. The As(1)-As(2) bond length is 2.46 Å. In the second As site, As(2) is bonded to three equivalent Rh(1) and one As(1) atom to form distorted AsAsRh3 tetrahedra that share corners with three equivalent Rh(1)As6 octahedra, corners with four equivalent As(2)AsRh3 tetrahedra, corners with nine equivalent As(1)AsRh3 tetrahedra, and  an edgeedge with one As(2)AsRh3 tetrahedra. The corner-sharing octahedral tilt angles range from 73-78°.