NiSnP2O9 crystallizes in the triclinic P-1 space group. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(4), two equivalent O(6), and two equivalent O(7) atoms to form NiO6 octahedra that share corners with two equivalent Sn(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles are 52°. In the second Ni site, Ni(2) is bonded to two equivalent O(2), two equivalent O(5), and two equivalent O(8) atoms to form NiO6 octahedra that share corners with two equivalent Sn(2)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and edges with two equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles are 53°. In the third Ni site, Ni(3) is bonded to two equivalent O(1), two equivalent O(5), and two equivalent O(8) atoms to form NiO6 octahedra that share corners with two equivalent Sn(2)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and edges with two equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles are 53°. In the fourth Ni site, Ni(4) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form NiO6 octahedra that share corners with two equivalent Sn(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 53°. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one O(13), one O(14), one O(16), one O(18), one O(7), and one O(9) atom to form SnO6 octahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(4)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-53°. In the second Sn site, Sn(2) is bonded to one O(10), one O(11), one O(12), one O(15), one O(17), and one O(8) atom to form SnO6 octahedra that share  a cornercorner with one Ni(2)O6 octahedra,  a cornercorner with one Ni(3)O6 octahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(13), one O(14), one O(18), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(4)O6 octahedra, and corners with three equivalent Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-51°. In the second P site, P(2) is bonded to one O(11), one O(12), one O(17), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra,  a cornercorner with one Ni(3)O6 octahedra, and corners with three equivalent Sn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-51°. In the third P site, P(3) is bonded to one O(1), one O(16), one O(2), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra,  a cornercorner with one Ni(3)O6 octahedra, and  an edgeedge with one Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-50°. In the fourth P site, P(4) is bonded to one O(10), one O(15), one O(3), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(4)O6 octahedra, and  an edgeedge with one Sn(2)O6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Ni(3) and one P(3) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Ni(2) and one P(3) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Ni(4) and one P(4) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Ni(1) and one P(4) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ni(2), one Ni(3), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(4), and one P(1) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Ni(1), one Ni(4), and one Sn(1) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Ni(2), one Ni(3), and one Sn(2) atom. In the ninth O site, O(9) is bonded in an L-shaped geometry to one Sn(1) and one P(3) atom. In the tenth O site, O(10) is bonded in an L-shaped geometry to one Sn(2) and one P(4) atom. In the eleventh O site, O(11) is bonded in a distorted bent 150 degrees geometry to one Sn(2) and one P(2) atom. In the twelfth O site, O(12) is bonded in a distorted bent 150 degrees geometry to one Sn(2) and one P(2) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 150 degrees geometry to one Sn(1) and one P(1) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 150 degrees geometry to one Sn(1) and one P(1) atom. In the fifteenth O site, O(15) is bonded in an L-shaped geometry to one Sn(2) and one P(4) atom. In the sixteenth O site, O(16) is bonded in an L-shaped geometry to one Sn(1) and one P(3) atom. In the seventeenth O site, O(17) is bonded in a linear geometry to one Sn(2) and one P(2) atom. In the eighteenth O site, O(18) is bonded in a linear geometry to one Sn(1) and one P(1) atom.
NiSnP2O9 crystallizes in the triclinic P-1 space group. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(4), two equivalent O(6), and two equivalent O(7) atoms to form NiO6 octahedra that share corners with two equivalent Sn(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles are 52°. Both Ni(1)-O(4) bond lengths are 1.94 Å. Both Ni(1)-O(6) bond lengths are 2.11 Å. Both Ni(1)-O(7) bond lengths are 2.00 Å. In the second Ni site, Ni(2) is bonded to two equivalent O(2), two equivalent O(5), and two equivalent O(8) atoms to form NiO6 octahedra that share corners with two equivalent Sn(2)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and edges with two equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles are 53°. Both Ni(2)-O(2) bond lengths are 1.93 Å. Both Ni(2)-O(5) bond lengths are 2.09 Å. Both Ni(2)-O(8) bond lengths are 2.03 Å. In the third Ni site, Ni(3) is bonded to two equivalent O(1), two equivalent O(5), and two equivalent O(8) atoms to form NiO6 octahedra that share corners with two equivalent Sn(2)O6 octahedra, corners with two equivalent P(2)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and edges with two equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles are 53°. Both Ni(3)-O(1) bond lengths are 1.93 Å. Both Ni(3)-O(5) bond lengths are 2.11 Å. Both Ni(3)-O(8) bond lengths are 2.01 Å. In the fourth Ni site, Ni(4) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form NiO6 octahedra that share corners with two equivalent Sn(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 53°. Both Ni(4)-O(3) bond lengths are 1.94 Å. Both Ni(4)-O(6) bond lengths are 2.09 Å. Both Ni(4)-O(7) bond lengths are 2.04 Å. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one O(13), one O(14), one O(16), one O(18), one O(7), and one O(9) atom to form SnO6 octahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(4)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-53°. The Sn(1)-O(13) bond length is 2.01 Å. The Sn(1)-O(14) bond length is 2.01 Å. The Sn(1)-O(16) bond length is 2.18 Å. The Sn(1)-O(18) bond length is 2.04 Å. The Sn(1)-O(7) bond length is 2.05 Å. The Sn(1)-O(9) bond length is 2.17 Å. In the second Sn site, Sn(2) is bonded to one O(10), one O(11), one O(12), one O(15), one O(17), and one O(8) atom to form SnO6 octahedra that share  a cornercorner with one Ni(2)O6 octahedra,  a cornercorner with one Ni(3)O6 octahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. The Sn(2)-O(10) bond length is 2.16 Å. The Sn(2)-O(11) bond length is 2.01 Å. The Sn(2)-O(12) bond length is 2.01 Å. The Sn(2)-O(15) bond length is 2.18 Å. The Sn(2)-O(17) bond length is 2.04 Å. The Sn(2)-O(8) bond length is 2.06 Å. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(13), one O(14), one O(18), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(4)O6 octahedra, and corners with three equivalent Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-51°. The P(1)-O(13) bond length is 1.54 Å. The P(1)-O(14) bond length is 1.54 Å. The P(1)-O(18) bond length is 1.52 Å. The P(1)-O(6) bond length is 1.55 Å. In the second P site, P(2) is bonded to one O(11), one O(12), one O(17), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra,  a cornercorner with one Ni(3)O6 octahedra, and corners with three equivalent Sn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-51°. The P(2)-O(11) bond length is 1.54 Å. The P(2)-O(12) bond length is 1.54 Å. The P(2)-O(17) bond length is 1.53 Å. The P(2)-O(5) bond length is 1.55 Å. In the third P site, P(3) is bonded to one O(1), one O(16), one O(2), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra,  a cornercorner with one Ni(3)O6 octahedra, and  an edgeedge with one Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-50°. The P(3)-O(1) bond length is 1.55 Å. The P(3)-O(16) bond length is 1.57 Å. The P(3)-O(2) bond length is 1.55 Å. The P(3)-O(9) bond length is 1.56 Å. In the fourth P site, P(4) is bonded to one O(10), one O(15), one O(3), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(4)O6 octahedra, and  an edgeedge with one Sn(2)O6 octahedra. The corner-sharing octahedral tilt angles are 50°. The P(4)-O(10) bond length is 1.56 Å. The P(4)-O(15) bond length is 1.57 Å. The P(4)-O(3) bond length is 1.55 Å. The P(4)-O(4) bond length is 1.55 Å. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Ni(3) and one P(3) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Ni(2) and one P(3) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Ni(4) and one P(4) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Ni(1) and one P(4) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ni(2), one Ni(3), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(4), and one P(1) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Ni(1), one Ni(4), and one Sn(1) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Ni(2), one Ni(3), and one Sn(2) atom. In the ninth O site, O(9) is bonded in an L-shaped geometry to one Sn(1) and one P(3) atom. In the tenth O site, O(10) is bonded in an L-shaped geometry to one Sn(2) and one P(4) atom. In the eleventh O site, O(11) is bonded in a distorted bent 150 degrees geometry to one Sn(2) and one P(2) atom. In the twelfth O site, O(12) is bonded in a distorted bent 150 degrees geometry to one Sn(2) and one P(2) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 150 degrees geometry to one Sn(1) and one P(1) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 150 degrees geometry to one Sn(1) and one P(1) atom. In the fifteenth O site, O(15) is bonded in an L-shaped geometry to one Sn(2) and one P(4) atom. In the sixteenth O site, O(16) is bonded in an L-shaped geometry to one Sn(1) and one P(3) atom. In the seventeenth O site, O(17) is bonded in a linear geometry to one Sn(2) and one P(2) atom. In the eighteenth O site, O(18) is bonded in a linear geometry to one Sn(1) and one P(1) atom.