ULa2As3 is Caswellsilverite-like structured and crystallizes in the orthorhombic Immm space group. U(1) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form UAs6 octahedra that share corners with two equivalent U(1)As6 octahedra, corners with four equivalent La(1)As6 octahedra, edges with two equivalent U(1)As6 octahedra, and edges with ten equivalent La(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. La(1) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form LaAs6 octahedra that share corners with two equivalent U(1)As6 octahedra, corners with four equivalent La(1)As6 octahedra, edges with five equivalent U(1)As6 octahedra, and edges with seven equivalent La(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. There are two inequivalent As sites. In the first As site, As(1) is bonded to two equivalent U(1) and four equivalent La(1) atoms to form a mixture of corner and edge-sharing AsLa4U2 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the second As site, As(2) is bonded to two equivalent U(1) and four equivalent La(1) atoms to form a mixture of corner and edge-sharing AsLa4U2 octahedra. The corner-sharing octahedral tilt angles range from 0-7°.
ULa2As3 is Caswellsilverite-like structured and crystallizes in the orthorhombic Immm space group. U(1) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form UAs6 octahedra that share corners with two equivalent U(1)As6 octahedra, corners with four equivalent La(1)As6 octahedra, edges with two equivalent U(1)As6 octahedra, and edges with ten equivalent La(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. Both U(1)-As(1) bond lengths are 3.03 Å. All U(1)-As(2) bond lengths are 2.92 Å. La(1) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form LaAs6 octahedra that share corners with two equivalent U(1)As6 octahedra, corners with four equivalent La(1)As6 octahedra, edges with five equivalent U(1)As6 octahedra, and edges with seven equivalent La(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. Both La(1)-As(1) bond lengths are 3.04 Å. There are two shorter (3.03 Å) and two longer (3.12 Å) La(1)-As(2) bond lengths. There are two inequivalent As sites. In the first As site, As(1) is bonded to two equivalent U(1) and four equivalent La(1) atoms to form a mixture of corner and edge-sharing AsLa4U2 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the second As site, As(2) is bonded to two equivalent U(1) and four equivalent La(1) atoms to form a mixture of corner and edge-sharing AsLa4U2 octahedra. The corner-sharing octahedral tilt angles range from 0-7°.