Nb2B3 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent B(3), four equivalent B(2), and six equivalent B(1) atoms to form a mixture of edge and face-sharing NbB12 cuboctahedra. In the second Nb site, Nb(2) is bonded in a 7-coordinate geometry to two equivalent B(2) and five equivalent B(3) atoms. There are three inequivalent B sites. In the first B site, B(1) is bonded in a 9-coordinate geometry to six equivalent Nb(1), one B(2), and two equivalent B(1) atoms. In the second B site, B(2) is bonded in a 9-coordinate geometry to two equivalent Nb(2), four equivalent Nb(1), one B(1), and two equivalent B(3) atoms. In the third B site, B(3) is bonded in a 9-coordinate geometry to two equivalent Nb(1), five equivalent Nb(2), and two equivalent B(2) atoms.
Nb2B3 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent B(3), four equivalent B(2), and six equivalent B(1) atoms to form a mixture of edge and face-sharing NbB12 cuboctahedra. Both Nb(1)-B(3) bond lengths are 2.51 Å. All Nb(1)-B(2) bond lengths are 2.46 Å. There are two shorter (2.45 Å) and four longer (2.46 Å) Nb(1)-B(1) bond lengths. In the second Nb site, Nb(2) is bonded in a 7-coordinate geometry to two equivalent B(2) and five equivalent B(3) atoms. Both Nb(2)-B(2) bond lengths are 2.38 Å. There are four shorter (2.40 Å) and one longer (2.60 Å) Nb(2)-B(3) bond length. There are three inequivalent B sites. In the first B site, B(1) is bonded in a 9-coordinate geometry to six equivalent Nb(1), one B(2), and two equivalent B(1) atoms. The B(1)-B(2) bond length is 1.82 Å. Both B(1)-B(1) bond lengths are 1.81 Å. In the second B site, B(2) is bonded in a 9-coordinate geometry to two equivalent Nb(2), four equivalent Nb(1), one B(1), and two equivalent B(3) atoms. Both B(2)-B(3) bond lengths are 1.84 Å. In the third B site, B(3) is bonded in a 9-coordinate geometry to two equivalent Nb(1), five equivalent Nb(2), and two equivalent B(2) atoms.