Ca2TaN3 crystallizes in the orthorhombic Cmce space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to two equivalent N(1), two equivalent N(3), and three equivalent N(2) atoms. In the second Ca site, Ca(2) is bonded to two equivalent N(2), two equivalent N(3), and three equivalent N(1) atoms to form distorted CaN7 pentagonal bipyramids that share corners with four equivalent Ca(2)N7 pentagonal bipyramids,  a cornercorner with one Ta(1)N4 tetrahedra, edges with three equivalent Ca(2)N7 pentagonal bipyramids, and edges with four equivalent Ta(1)N4 tetrahedra. Ta(1) is bonded to one N(1), one N(2), and two equivalent N(3) atoms to form TaN4 tetrahedra that share  a cornercorner with one Ca(2)N7 pentagonal bipyramid, corners with two equivalent Ta(1)N4 tetrahedra, and edges with four equivalent Ca(2)N7 pentagonal bipyramids. There are three inequivalent N sites. In the first N site, N(3) is bonded in a 4-coordinate geometry to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Ta(1) atoms. In the second N site, N(1) is bonded in a 6-coordinate geometry to two equivalent Ca(1), three equivalent Ca(2), and one Ta(1) atom. In the third N site, N(2) is bonded to two equivalent Ca(2), three equivalent Ca(1), and one Ta(1) atom to form a mixture of distorted corner and edge-sharing NCa5Ta octahedra. The corner-sharing octahedral tilt angles are 19°.
Ca2TaN3 crystallizes in the orthorhombic Cmce space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to two equivalent N(1), two equivalent N(3), and three equivalent N(2) atoms. There is one shorter (2.37 Å) and one longer (2.62 Å) Ca(1)-N(1) bond length. Both Ca(1)-N(3) bond lengths are 3.06 Å. There is one shorter (2.57 Å) and two longer (2.95 Å) Ca(1)-N(2) bond lengths. In the second Ca site, Ca(2) is bonded to two equivalent N(2), two equivalent N(3), and three equivalent N(1) atoms to form distorted CaN7 pentagonal bipyramids that share corners with four equivalent Ca(2)N7 pentagonal bipyramids,  a cornercorner with one Ta(1)N4 tetrahedra, edges with three equivalent Ca(2)N7 pentagonal bipyramids, and edges with four equivalent Ta(1)N4 tetrahedra. There is one shorter (2.40 Å) and one longer (2.58 Å) Ca(2)-N(2) bond length. Both Ca(2)-N(3) bond lengths are 2.54 Å. There is one shorter (2.65 Å) and two longer (3.00 Å) Ca(2)-N(1) bond lengths. Ta(1) is bonded to one N(1), one N(2), and two equivalent N(3) atoms to form TaN4 tetrahedra that share  a cornercorner with one Ca(2)N7 pentagonal bipyramid, corners with two equivalent Ta(1)N4 tetrahedra, and edges with four equivalent Ca(2)N7 pentagonal bipyramids. The Ta(1)-N(1) bond length is 1.90 Å. The Ta(1)-N(2) bond length is 1.94 Å. Both Ta(1)-N(3) bond lengths are 1.95 Å. There are three inequivalent N sites. In the first N site, N(3) is bonded in a 4-coordinate geometry to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Ta(1) atoms. In the second N site, N(1) is bonded in a 6-coordinate geometry to two equivalent Ca(1), three equivalent Ca(2), and one Ta(1) atom. In the third N site, N(2) is bonded to two equivalent Ca(2), three equivalent Ca(1), and one Ta(1) atom to form a mixture of distorted corner and edge-sharing NCa5Ta octahedra. The corner-sharing octahedral tilt angles are 19°.