Ca3Nb3N5 crystallizes in the triclinic P-1 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 4-coordinate geometry to one N(3), one N(4), and two equivalent N(2) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one N(3), one N(4), two equivalent N(1), and two equivalent N(5) atoms. In the third Ca site, Ca(3) is bonded in a 5-coordinate geometry to one N(1), one N(2), one N(5), and two equivalent N(3) atoms. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one N(1), one N(5), and two equivalent N(3) atoms to form a mixture of corner and edge-sharing NbN4 tetrahedra. In the second Nb site, Nb(2) is bonded to one N(1), one N(2), and two equivalent N(4) atoms to form a mixture of distorted corner and edge-sharing NbN4 trigonal pyramids. In the third Nb site, Nb(3) is bonded to one N(1), one N(2), one N(4), and one N(5) atom to form a mixture of distorted corner and edge-sharing NbN4 tetrahedra. There are five inequivalent N sites. In the first N site, N(1) is bonded to one Ca(3), two equivalent Ca(2), one Nb(1), one Nb(2), and one Nb(3) atom to form NCa3Nb3 octahedra that share corners with three equivalent N(3)Ca4Nb2 octahedra, corners with three equivalent N(4)Ca2Nb3 trigonal bipyramids,  an edgeedge with one N(1)Ca3Nb3 octahedra,  an edgeedge with one N(4)Ca2Nb3 trigonal bipyramid, and  a faceface with one N(3)Ca4Nb2 octahedra. The corner-sharing octahedral tilt angles range from 35-64°. In the second N site, N(2) is bonded in a 5-coordinate geometry to one Ca(3), two equivalent Ca(1), one Nb(2), and one Nb(3) atom. In the third N site, N(3) is bonded to one Ca(1), one Ca(2), two equivalent Ca(3), and two equivalent Nb(1) atoms to form NCa4Nb2 octahedra that share corners with three equivalent N(1)Ca3Nb3 octahedra, corners with two equivalent N(4)Ca2Nb3 trigonal bipyramids, edges with two equivalent N(3)Ca4Nb2 octahedra, and  a faceface with one N(1)Ca3Nb3 octahedra. The corner-sharing octahedral tilt angles range from 35-64°. In the fourth N site, N(4) is bonded to one Ca(1), one Ca(2), one Nb(3), and two equivalent Nb(2) atoms to form distorted NCa2Nb3 trigonal bipyramids that share corners with two equivalent N(3)Ca4Nb2 octahedra, corners with three equivalent N(1)Ca3Nb3 octahedra,  an edgeedge with one N(1)Ca3Nb3 octahedra, and  an edgeedge with one N(4)Ca2Nb3 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 13-64°. In the fifth N site, N(5) is bonded in a 5-coordinate geometry to one Ca(3), two equivalent Ca(2), one Nb(1), and one Nb(3) atom.
Ca3Nb3N5 crystallizes in the triclinic P-1 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 4-coordinate geometry to one N(3), one N(4), and two equivalent N(2) atoms. The Ca(1)-N(3) bond length is 2.39 Å. The Ca(1)-N(4) bond length is 2.41 Å. There is one shorter (2.47 Å) and one longer (2.68 Å) Ca(1)-N(2) bond length. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one N(3), one N(4), two equivalent N(1), and two equivalent N(5) atoms. The Ca(2)-N(3) bond length is 2.43 Å. The Ca(2)-N(4) bond length is 2.59 Å. There is one shorter (2.54 Å) and one longer (2.69 Å) Ca(2)-N(1) bond length. There is one shorter (2.40 Å) and one longer (2.83 Å) Ca(2)-N(5) bond length. In the third Ca site, Ca(3) is bonded in a 5-coordinate geometry to one N(1), one N(2), one N(5), and two equivalent N(3) atoms. The Ca(3)-N(1) bond length is 2.71 Å. The Ca(3)-N(2) bond length is 2.41 Å. The Ca(3)-N(5) bond length is 2.93 Å. There is one shorter (2.46 Å) and one longer (2.68 Å) Ca(3)-N(3) bond length. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one N(1), one N(5), and two equivalent N(3) atoms to form a mixture of corner and edge-sharing NbN4 tetrahedra. The Nb(1)-N(1) bond length is 2.09 Å. The Nb(1)-N(5) bond length is 1.95 Å. There is one shorter (2.14 Å) and one longer (2.16 Å) Nb(1)-N(3) bond length. In the second Nb site, Nb(2) is bonded to one N(1), one N(2), and two equivalent N(4) atoms to form a mixture of distorted corner and edge-sharing NbN4 trigonal pyramids. The Nb(2)-N(1) bond length is 2.17 Å. The Nb(2)-N(2) bond length is 2.28 Å. There is one shorter (2.01 Å) and one longer (2.29 Å) Nb(2)-N(4) bond length. In the third Nb site, Nb(3) is bonded to one N(1), one N(2), one N(4), and one N(5) atom to form a mixture of distorted corner and edge-sharing NbN4 tetrahedra. The Nb(3)-N(1) bond length is 2.07 Å. The Nb(3)-N(2) bond length is 1.97 Å. The Nb(3)-N(4) bond length is 2.06 Å. The Nb(3)-N(5) bond length is 2.10 Å. There are five inequivalent N sites. In the first N site, N(1) is bonded to one Ca(3), two equivalent Ca(2), one Nb(1), one Nb(2), and one Nb(3) atom to form NCa3Nb3 octahedra that share corners with three equivalent N(3)Ca4Nb2 octahedra, corners with three equivalent N(4)Ca2Nb3 trigonal bipyramids,  an edgeedge with one N(1)Ca3Nb3 octahedra,  an edgeedge with one N(4)Ca2Nb3 trigonal bipyramid, and  a faceface with one N(3)Ca4Nb2 octahedra. The corner-sharing octahedral tilt angles range from 35-64°. In the second N site, N(2) is bonded in a 5-coordinate geometry to one Ca(3), two equivalent Ca(1), one Nb(2), and one Nb(3) atom. In the third N site, N(3) is bonded to one Ca(1), one Ca(2), two equivalent Ca(3), and two equivalent Nb(1) atoms to form NCa4Nb2 octahedra that share corners with three equivalent N(1)Ca3Nb3 octahedra, corners with two equivalent N(4)Ca2Nb3 trigonal bipyramids, edges with two equivalent N(3)Ca4Nb2 octahedra, and  a faceface with one N(1)Ca3Nb3 octahedra. The corner-sharing octahedral tilt angles range from 35-64°. In the fourth N site, N(4) is bonded to one Ca(1), one Ca(2), one Nb(3), and two equivalent Nb(2) atoms to form distorted NCa2Nb3 trigonal bipyramids that share corners with two equivalent N(3)Ca4Nb2 octahedra, corners with three equivalent N(1)Ca3Nb3 octahedra,  an edgeedge with one N(1)Ca3Nb3 octahedra, and  an edgeedge with one N(4)Ca2Nb3 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 13-64°. In the fifth N site, N(5) is bonded in a 5-coordinate geometry to one Ca(3), two equivalent Ca(2), one Nb(1), and one Nb(3) atom.