Pr8Ni4O17 crystallizes in the triclinic P1 space group. There are eight inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 6-coordinate geometry to one O(10), one O(15), one O(17), one O(3), one O(5), and one O(6) atom. In the second Pr site, Pr(2) is bonded in a 7-coordinate geometry to one O(10), one O(11), one O(14), one O(15), one O(17), one O(6), and one O(9) atom. In the third Pr site, Pr(3) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(14), one O(16), one O(2), one O(4), and one O(8) atom. In the fourth Pr site, Pr(4) is bonded in a 7-coordinate geometry to one O(10), one O(13), one O(17), one O(3), one O(5), one O(6), and one O(9) atom. In the fifth Pr site, Pr(5) is bonded in a 7-coordinate geometry to one O(1), one O(12), one O(13), one O(3), one O(5), one O(7), and one O(8) atom. In the sixth Pr site, Pr(6) is bonded in a 6-coordinate geometry to one O(10), one O(14), one O(15), one O(2), one O(6), and one O(9) atom. In the seventh Pr site, Pr(7) is bonded in a 7-coordinate geometry to one O(11), one O(14), one O(16), one O(2), one O(4), one O(7), and one O(8) atom. In the eighth Pr site, Pr(8) is bonded in a 7-coordinate geometry to one O(1), one O(12), one O(13), one O(16), one O(3), one O(5), and one O(7) atom. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(11), one O(14), one O(15), one O(16), one O(2), and one O(4) atom to form distorted corner-sharing NiO6 octahedra. In the second Ni site, Ni(2) is bonded to one O(1), one O(12), one O(13), one O(17), one O(3), and one O(5) atom to form corner-sharing NiO6 octahedra. In the third Ni site, Ni(3) is bonded to one O(12), one O(13), one O(3), one O(5), and one O(7) atom to form distorted corner-sharing NiO5 square pyramids. The corner-sharing octahedral tilt angles range from 7-33°. In the fourth Ni site, Ni(4) is bonded to one O(11), one O(14), one O(2), one O(4), and one O(8) atom to form distorted corner-sharing NiO5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 7-31°. There are seventeen inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Pr(3), one Pr(5), one Pr(8), and one Ni(2) atom. In the second O site, O(2) is bonded to one Pr(3), one Pr(6), one Pr(7), one Ni(1), and one Ni(4) atom to form OPr3Ni2 trigonal bipyramids that share  a cornercorner with one O(6)Pr4 tetrahedra,  a cornercorner with one O(10)Pr4 trigonal pyramid, and  an edgeedge with one O(15)Pr3Ni trigonal pyramid. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Pr(1), one Pr(4), one Pr(5), one Pr(8), one Ni(2), and one Ni(3) atom. In the fourth O site, O(4) is bonded in a distorted see-saw-like geometry to one Pr(3), one Pr(7), one Ni(1), and one Ni(4) atom. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Pr(1), one Pr(4), one Pr(5), one Pr(8), one Ni(2), and one Ni(3) atom. In the sixth O site, O(6) is bonded to one Pr(1), one Pr(2), one Pr(4), and one Pr(6) atom to form OPr4 tetrahedra that share  a cornercorner with one O(13)Pr3Ni2 trigonal bipyramid,  a cornercorner with one O(2)Pr3Ni2 trigonal bipyramid,  a cornercorner with one O(15)Pr3Ni trigonal pyramid,  an edgeedge with one O(15)Pr3Ni trigonal pyramid, and edges with two equivalent O(10)Pr4 trigonal pyramids. In the seventh O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to one Pr(5), one Pr(7), one Pr(8), and one Ni(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Pr(3), one Pr(5), one Pr(7), and one Ni(4) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Pr(2), one Pr(4), and one Pr(6) atom. In the tenth O site, O(10) is bonded to one Pr(1), one Pr(2), one Pr(4), and one Pr(6) atom to form distorted OPr4 trigonal pyramids that share  a cornercorner with one O(13)Pr3Ni2 trigonal bipyramid,  a cornercorner with one O(2)Pr3Ni2 trigonal bipyramid, corners with three equivalent O(15)Pr3Ni trigonal pyramids, and edges with two equivalent O(6)Pr4 tetrahedra. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one Pr(2), one Pr(3), one Pr(7), one Ni(1), and one Ni(4) atom. In the twelfth O site, O(12) is bonded to one Pr(5), one Pr(8), one Ni(2), and one Ni(3) atom to form distorted edge-sharing OPr2Ni2 trigonal pyramids. In the thirteenth O site, O(13) is bonded to one Pr(4), one Pr(5), one Pr(8), one Ni(2), and one Ni(3) atom to form distorted OPr3Ni2 trigonal bipyramids that share  a cornercorner with one O(6)Pr4 tetrahedra,  a cornercorner with one O(10)Pr4 trigonal pyramid, and edges with two equivalent O(12)Pr2Ni2 trigonal pyramids. In the fourteenth O site, O(14) is bonded in a 6-coordinate geometry to one Pr(2), one Pr(3), one Pr(6), one Pr(7), one Ni(1), and one Ni(4) atom. In the fifteenth O site, O(15) is bonded to one Pr(1), one Pr(2), one Pr(6), and one Ni(1) atom to form distorted OPr3Ni trigonal pyramids that share  a cornercorner with one O(6)Pr4 tetrahedra, corners with three equivalent O(10)Pr4 trigonal pyramids,  an edgeedge with one O(6)Pr4 tetrahedra, and  an edgeedge with one O(2)Pr3Ni2 trigonal bipyramid. In the sixteenth O site, O(16) is bonded in a see-saw-like geometry to one Pr(3), one Pr(7), one Pr(8), and one Ni(1) atom. In the seventeenth O site, O(17) is bonded in a 4-coordinate geometry to one Pr(1), one Pr(2), one Pr(4), and one Ni(2) atom.
Pr8Ni4O17 crystallizes in the triclinic P1 space group. There are eight inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 6-coordinate geometry to one O(10), one O(15), one O(17), one O(3), one O(5), and one O(6) atom. The Pr(1)-O(10) bond length is 2.24 Å. The Pr(1)-O(15) bond length is 2.57 Å. The Pr(1)-O(17) bond length is 2.35 Å. The Pr(1)-O(3) bond length is 2.59 Å. The Pr(1)-O(5) bond length is 2.73 Å. The Pr(1)-O(6) bond length is 2.41 Å. In the second Pr site, Pr(2) is bonded in a 7-coordinate geometry to one O(10), one O(11), one O(14), one O(15), one O(17), one O(6), and one O(9) atom. The Pr(2)-O(10) bond length is 2.52 Å. The Pr(2)-O(11) bond length is 2.54 Å. The Pr(2)-O(14) bond length is 2.67 Å. The Pr(2)-O(15) bond length is 2.34 Å. The Pr(2)-O(17) bond length is 2.61 Å. The Pr(2)-O(6) bond length is 2.45 Å. The Pr(2)-O(9) bond length is 2.33 Å. In the third Pr site, Pr(3) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(14), one O(16), one O(2), one O(4), and one O(8) atom. The Pr(3)-O(1) bond length is 2.36 Å. The Pr(3)-O(11) bond length is 2.56 Å. The Pr(3)-O(14) bond length is 2.67 Å. The Pr(3)-O(16) bond length is 2.40 Å. The Pr(3)-O(2) bond length is 2.51 Å. The Pr(3)-O(4) bond length is 2.39 Å. The Pr(3)-O(8) bond length is 2.41 Å. In the fourth Pr site, Pr(4) is bonded in a 7-coordinate geometry to one O(10), one O(13), one O(17), one O(3), one O(5), one O(6), and one O(9) atom. The Pr(4)-O(10) bond length is 2.33 Å. The Pr(4)-O(13) bond length is 2.61 Å. The Pr(4)-O(17) bond length is 2.53 Å. The Pr(4)-O(3) bond length is 2.59 Å. The Pr(4)-O(5) bond length is 3.01 Å. The Pr(4)-O(6) bond length is 2.36 Å. The Pr(4)-O(9) bond length is 2.28 Å. In the fifth Pr site, Pr(5) is bonded in a 7-coordinate geometry to one O(1), one O(12), one O(13), one O(3), one O(5), one O(7), and one O(8) atom. The Pr(5)-O(1) bond length is 2.39 Å. The Pr(5)-O(12) bond length is 2.46 Å. The Pr(5)-O(13) bond length is 2.40 Å. The Pr(5)-O(3) bond length is 2.81 Å. The Pr(5)-O(5) bond length is 2.53 Å. The Pr(5)-O(7) bond length is 2.57 Å. The Pr(5)-O(8) bond length is 2.27 Å. In the sixth Pr site, Pr(6) is bonded in a 6-coordinate geometry to one O(10), one O(14), one O(15), one O(2), one O(6), and one O(9) atom. The Pr(6)-O(10) bond length is 2.39 Å. The Pr(6)-O(14) bond length is 2.51 Å. The Pr(6)-O(15) bond length is 2.40 Å. The Pr(6)-O(2) bond length is 2.56 Å. The Pr(6)-O(6) bond length is 2.34 Å. The Pr(6)-O(9) bond length is 2.26 Å. In the seventh Pr site, Pr(7) is bonded in a 7-coordinate geometry to one O(11), one O(14), one O(16), one O(2), one O(4), one O(7), and one O(8) atom. The Pr(7)-O(11) bond length is 2.48 Å. The Pr(7)-O(14) bond length is 2.86 Å. The Pr(7)-O(16) bond length is 2.37 Å. The Pr(7)-O(2) bond length is 2.47 Å. The Pr(7)-O(4) bond length is 2.39 Å. The Pr(7)-O(7) bond length is 2.29 Å. The Pr(7)-O(8) bond length is 2.58 Å. In the eighth Pr site, Pr(8) is bonded in a 7-coordinate geometry to one O(1), one O(12), one O(13), one O(16), one O(3), one O(5), and one O(7) atom. The Pr(8)-O(1) bond length is 2.47 Å. The Pr(8)-O(12) bond length is 2.39 Å. The Pr(8)-O(13) bond length is 2.48 Å. The Pr(8)-O(16) bond length is 2.39 Å. The Pr(8)-O(3) bond length is 2.56 Å. The Pr(8)-O(5) bond length is 2.74 Å. The Pr(8)-O(7) bond length is 2.40 Å. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(11), one O(14), one O(15), one O(16), one O(2), and one O(4) atom to form distorted corner-sharing NiO6 octahedra. The Ni(1)-O(11) bond length is 2.02 Å. The Ni(1)-O(14) bond length is 2.56 Å. The Ni(1)-O(15) bond length is 2.10 Å. The Ni(1)-O(16) bond length is 2.18 Å. The Ni(1)-O(2) bond length is 2.14 Å. The Ni(1)-O(4) bond length is 2.07 Å. In the second Ni site, Ni(2) is bonded to one O(1), one O(12), one O(13), one O(17), one O(3), and one O(5) atom to form corner-sharing NiO6 octahedra. The Ni(2)-O(1) bond length is 2.09 Å. The Ni(2)-O(12) bond length is 2.08 Å. The Ni(2)-O(13) bond length is 2.26 Å. The Ni(2)-O(17) bond length is 1.99 Å. The Ni(2)-O(3) bond length is 2.03 Å. The Ni(2)-O(5) bond length is 2.24 Å. In the third Ni site, Ni(3) is bonded to one O(12), one O(13), one O(3), one O(5), and one O(7) atom to form distorted corner-sharing NiO5 square pyramids. The corner-sharing octahedral tilt angles range from 7-33°. The Ni(3)-O(12) bond length is 2.02 Å. The Ni(3)-O(13) bond length is 1.98 Å. The Ni(3)-O(3) bond length is 2.46 Å. The Ni(3)-O(5) bond length is 1.94 Å. The Ni(3)-O(7) bond length is 2.01 Å. In the fourth Ni site, Ni(4) is bonded to one O(11), one O(14), one O(2), one O(4), and one O(8) atom to form distorted corner-sharing NiO5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 7-31°. The Ni(4)-O(11) bond length is 2.15 Å. The Ni(4)-O(14) bond length is 1.92 Å. The Ni(4)-O(2) bond length is 2.08 Å. The Ni(4)-O(4) bond length is 1.97 Å. The Ni(4)-O(8) bond length is 2.05 Å. There are seventeen inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Pr(3), one Pr(5), one Pr(8), and one Ni(2) atom. In the second O site, O(2) is bonded to one Pr(3), one Pr(6), one Pr(7), one Ni(1), and one Ni(4) atom to form OPr3Ni2 trigonal bipyramids that share  a cornercorner with one O(6)Pr4 tetrahedra,  a cornercorner with one O(10)Pr4 trigonal pyramid, and  an edgeedge with one O(15)Pr3Ni trigonal pyramid. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Pr(1), one Pr(4), one Pr(5), one Pr(8), one Ni(2), and one Ni(3) atom. In the fourth O site, O(4) is bonded in a distorted see-saw-like geometry to one Pr(3), one Pr(7), one Ni(1), and one Ni(4) atom. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Pr(1), one Pr(4), one Pr(5), one Pr(8), one Ni(2), and one Ni(3) atom. In the sixth O site, O(6) is bonded to one Pr(1), one Pr(2), one Pr(4), and one Pr(6) atom to form OPr4 tetrahedra that share  a cornercorner with one O(13)Pr3Ni2 trigonal bipyramid,  a cornercorner with one O(2)Pr3Ni2 trigonal bipyramid,  a cornercorner with one O(15)Pr3Ni trigonal pyramid,  an edgeedge with one O(15)Pr3Ni trigonal pyramid, and edges with two equivalent O(10)Pr4 trigonal pyramids. In the seventh O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to one Pr(5), one Pr(7), one Pr(8), and one Ni(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Pr(3), one Pr(5), one Pr(7), and one Ni(4) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Pr(2), one Pr(4), and one Pr(6) atom. In the tenth O site, O(10) is bonded to one Pr(1), one Pr(2), one Pr(4), and one Pr(6) atom to form distorted OPr4 trigonal pyramids that share  a cornercorner with one O(13)Pr3Ni2 trigonal bipyramid,  a cornercorner with one O(2)Pr3Ni2 trigonal bipyramid, corners with three equivalent O(15)Pr3Ni trigonal pyramids, and edges with two equivalent O(6)Pr4 tetrahedra. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one Pr(2), one Pr(3), one Pr(7), one Ni(1), and one Ni(4) atom. In the twelfth O site, O(12) is bonded to one Pr(5), one Pr(8), one Ni(2), and one Ni(3) atom to form distorted edge-sharing OPr2Ni2 trigonal pyramids. In the thirteenth O site, O(13) is bonded to one Pr(4), one Pr(5), one Pr(8), one Ni(2), and one Ni(3) atom to form distorted OPr3Ni2 trigonal bipyramids that share  a cornercorner with one O(6)Pr4 tetrahedra,  a cornercorner with one O(10)Pr4 trigonal pyramid, and edges with two equivalent O(12)Pr2Ni2 trigonal pyramids. In the fourteenth O site, O(14) is bonded in a 6-coordinate geometry to one Pr(2), one Pr(3), one Pr(6), one Pr(7), one Ni(1), and one Ni(4) atom. In the fifteenth O site, O(15) is bonded to one Pr(1), one Pr(2), one Pr(6), and one Ni(1) atom to form distorted OPr3Ni trigonal pyramids that share  a cornercorner with one O(6)Pr4 tetrahedra, corners with three equivalent O(10)Pr4 trigonal pyramids,  an edgeedge with one O(6)Pr4 tetrahedra, and  an edgeedge with one O(2)Pr3Ni2 trigonal bipyramid. In the sixteenth O site, O(16) is bonded in a see-saw-like geometry to one Pr(3), one Pr(7), one Pr(8), and one Ni(1) atom. In the seventeenth O site, O(17) is bonded in a 4-coordinate geometry to one Pr(1), one Pr(2), one Pr(4), and one Ni(2) atom.