ErTiFe11N crystallizes in the orthorhombic Imm2 space group. Er(1) is bonded in a linear geometry to one Ti(1), two equivalent Fe(6), eight equivalent Fe(4), and two equivalent N(1) atoms. Ti(1) is bonded in a 14-coordinate geometry to one Er(1), one Fe(5), two equivalent Fe(2), two equivalent Fe(3), four equivalent Fe(4), and four equivalent Fe(6) atoms. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a single-bond geometry to two equivalent Fe(6), four equivalent Fe(4), and one N(1) atom. In the second Fe site, Fe(2) is bonded in a single-bond geometry to two equivalent Ti(1), two equivalent Fe(6), four equivalent Fe(4), and one N(1) atom. In the third Fe site, Fe(3) is bonded in a single-bond geometry to one Ti(1), two equivalent Fe(6), four equivalent Fe(4), and one N(1) atom. In the fourth Fe site, Fe(4) is bonded to two equivalent Er(1), one Ti(1), one Fe(1), one Fe(2), one Fe(5), two equivalent Fe(3), two equivalent Fe(4), and two equivalent Fe(6) atoms to form distorted FeEr2TiFe9 cuboctahedra that share corners with ten equivalent Fe(4)Er2TiFe9 cuboctahedra, corners with two equivalent N(1)Er2Fe4 octahedra, edges with four equivalent Fe(4)Er2TiFe9 cuboctahedra, faces with six equivalent Fe(4)Er2TiFe9 cuboctahedra, and faces with two equivalent N(1)Er2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 67-70°. In the fifth Fe site, Fe(5) is bonded in a 1-coordinate geometry to one Ti(1), four equivalent Fe(4), and four equivalent Fe(6) atoms. In the sixth Fe site, Fe(6) is bonded in a 14-coordinate geometry to one Er(1), two equivalent Ti(1), one Fe(1), one Fe(2), one Fe(6), two equivalent Fe(3), two equivalent Fe(5), and four equivalent Fe(4) atoms. N(1) is bonded to two equivalent Er(1), one Fe(1), one Fe(2), and two equivalent Fe(3) atoms to form NEr2Fe4 octahedra that share corners with eight equivalent Fe(4)Er2TiFe9 cuboctahedra, corners with two equivalent N(1)Er2Fe4 octahedra, and faces with eight equivalent Fe(4)Er2TiFe9 cuboctahedra. The corner-sharing octahedral tilt angles are 2°.
ErTiFe11N crystallizes in the orthorhombic Imm2 space group. Er(1) is bonded in a linear geometry to one Ti(1), two equivalent Fe(6), eight equivalent Fe(4), and two equivalent N(1) atoms. The Er(1)-Ti(1) bond length is 3.18 Å. Both Er(1)-Fe(6) bond lengths are 3.09 Å. There are four shorter (3.21 Å) and four longer (3.31 Å) Er(1)-Fe(4) bond lengths. Both Er(1)-N(1) bond lengths are 2.39 Å. Ti(1) is bonded in a 14-coordinate geometry to one Er(1), one Fe(5), two equivalent Fe(2), two equivalent Fe(3), four equivalent Fe(4), and four equivalent Fe(6) atoms. The Ti(1)-Fe(5) bond length is 2.38 Å. Both Ti(1)-Fe(2) bond lengths are 2.68 Å. Both Ti(1)-Fe(3) bond lengths are 2.66 Å. All Ti(1)-Fe(4) bond lengths are 2.67 Å. All Ti(1)-Fe(6) bond lengths are 2.92 Å. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a single-bond geometry to two equivalent Fe(6), four equivalent Fe(4), and one N(1) atom. Both Fe(1)-Fe(6) bond lengths are 2.64 Å. All Fe(1)-Fe(4) bond lengths are 2.46 Å. The Fe(1)-N(1) bond length is 1.92 Å. In the second Fe site, Fe(2) is bonded in a single-bond geometry to two equivalent Ti(1), two equivalent Fe(6), four equivalent Fe(4), and one N(1) atom. Both Fe(2)-Fe(6) bond lengths are 2.67 Å. All Fe(2)-Fe(4) bond lengths are 2.49 Å. The Fe(2)-N(1) bond length is 1.91 Å. In the third Fe site, Fe(3) is bonded in a single-bond geometry to one Ti(1), two equivalent Fe(6), four equivalent Fe(4), and one N(1) atom. Both Fe(3)-Fe(6) bond lengths are 2.66 Å. There are two shorter (2.44 Å) and two longer (2.48 Å) Fe(3)-Fe(4) bond lengths. The Fe(3)-N(1) bond length is 1.92 Å. In the fourth Fe site, Fe(4) is bonded to two equivalent Er(1), one Ti(1), one Fe(1), one Fe(2), one Fe(5), two equivalent Fe(3), two equivalent Fe(4), and two equivalent Fe(6) atoms to form distorted FeEr2TiFe9 cuboctahedra that share corners with ten equivalent Fe(4)Er2TiFe9 cuboctahedra, corners with two equivalent N(1)Er2Fe4 octahedra, edges with four equivalent Fe(4)Er2TiFe9 cuboctahedra, faces with six equivalent Fe(4)Er2TiFe9 cuboctahedra, and faces with two equivalent N(1)Er2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 67-70°. The Fe(4)-Fe(5) bond length is 2.61 Å. There is one shorter (2.38 Å) and one longer (2.39 Å) Fe(4)-Fe(4) bond length. There is one shorter (2.61 Å) and one longer (2.63 Å) Fe(4)-Fe(6) bond length. In the fifth Fe site, Fe(5) is bonded in a 1-coordinate geometry to one Ti(1), four equivalent Fe(4), and four equivalent Fe(6) atoms. All Fe(5)-Fe(6) bond lengths are 2.95 Å. In the sixth Fe site, Fe(6) is bonded in a 14-coordinate geometry to one Er(1), two equivalent Ti(1), one Fe(1), one Fe(2), one Fe(6), two equivalent Fe(3), two equivalent Fe(5), and four equivalent Fe(4) atoms. The Fe(6)-Fe(6) bond length is 2.43 Å. N(1) is bonded to two equivalent Er(1), one Fe(1), one Fe(2), and two equivalent Fe(3) atoms to form NEr2Fe4 octahedra that share corners with eight equivalent Fe(4)Er2TiFe9 cuboctahedra, corners with two equivalent N(1)Er2Fe4 octahedra, and faces with eight equivalent Fe(4)Er2TiFe9 cuboctahedra. The corner-sharing octahedral tilt angles are 2°.