Tm(Ni2As)2 crystallizes in the tetragonal P4_2/mnm space group. Tm(1) is bonded to six equivalent As(1) atoms to form a mixture of distorted edge and corner-sharing TmAs6 octahedra. The corner-sharing octahedral tilt angles are 40°. Ni(1) is bonded in a 3-coordinate geometry to three equivalent As(1) atoms. As(1) is bonded in a 9-coordinate geometry to three equivalent Tm(1) and six equivalent Ni(1) atoms.
Tm(Ni2As)2 crystallizes in the tetragonal P4_2/mnm space group. Tm(1) is bonded to six equivalent As(1) atoms to form a mixture of distorted edge and corner-sharing TmAs6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are two shorter (2.86 Å) and four longer (2.89 Å) Tm(1)-As(1) bond lengths. Ni(1) is bonded in a 3-coordinate geometry to three equivalent As(1) atoms. All Ni(1)-As(1) bond lengths are 2.37 Å. As(1) is bonded in a 9-coordinate geometry to three equivalent Tm(1) and six equivalent Ni(1) atoms.