Mg2NbN3 is Enargite-like structured and crystallizes in the orthorhombic Cmc2_1 space group. Mg(1) is bonded to one N(2) and three equivalent N(1) atoms to form MgN4 tetrahedra that share corners with five equivalent Nb(1)N4 tetrahedra and corners with seven equivalent Mg(1)N4 tetrahedra. Nb(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form NbN4 tetrahedra that share corners with two equivalent Nb(1)N4 tetrahedra and corners with ten equivalent Mg(1)N4 tetrahedra. There are two inequivalent N sites. In the first N site, N(1) is bonded to three equivalent Mg(1) and one Nb(1) atom to form NMg3Nb tetrahedra that share corners with five equivalent N(2)Mg2Nb2 tetrahedra and corners with seven equivalent N(1)Mg3Nb tetrahedra. In the second N site, N(2) is bonded to two equivalent Mg(1) and two equivalent Nb(1) atoms to form NMg2Nb2 tetrahedra that share corners with two equivalent N(2)Mg2Nb2 tetrahedra and corners with ten equivalent N(1)Mg3Nb tetrahedra.
Mg2NbN3 is Enargite-like structured and crystallizes in the orthorhombic Cmc2_1 space group. Mg(1) is bonded to one N(2) and three equivalent N(1) atoms to form MgN4 tetrahedra that share corners with five equivalent Nb(1)N4 tetrahedra and corners with seven equivalent Mg(1)N4 tetrahedra. The Mg(1)-N(2) bond length is 2.15 Å. There are two shorter (2.10 Å) and one longer (2.13 Å) Mg(1)-N(1) bond length. Nb(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form NbN4 tetrahedra that share corners with two equivalent Nb(1)N4 tetrahedra and corners with ten equivalent Mg(1)N4 tetrahedra. Both Nb(1)-N(1) bond lengths are 1.92 Å. There is one shorter (2.01 Å) and one longer (2.03 Å) Nb(1)-N(2) bond length. There are two inequivalent N sites. In the first N site, N(1) is bonded to three equivalent Mg(1) and one Nb(1) atom to form NMg3Nb tetrahedra that share corners with five equivalent N(2)Mg2Nb2 tetrahedra and corners with seven equivalent N(1)Mg3Nb tetrahedra. In the second N site, N(2) is bonded to two equivalent Mg(1) and two equivalent Nb(1) atoms to form NMg2Nb2 tetrahedra that share corners with two equivalent N(2)Mg2Nb2 tetrahedra and corners with ten equivalent N(1)Mg3Nb tetrahedra.