MgPr2S4 is Aluminum carbonitride-like structured and crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one S(2), one S(3), one S(5), and one S(6) atom to form MgS4 tetrahedra that share  a cornercorner with one Mg(2)S6 octahedra, corners with two equivalent Pr(2)S6 octahedra, corners with three equivalent Pr(1)S5 trigonal bipyramids, and corners with three equivalent Pr(4)S5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 61-66°. In the second Mg site, Mg(2) is bonded to one S(2), one S(7), two equivalent S(1), and two equivalent S(8) atoms to form distorted MgS6 octahedra that share  a cornercorner with one Mg(1)S4 tetrahedra,  a cornercorner with one Pr(4)S5 trigonal bipyramid, corners with two equivalent Pr(1)S5 trigonal bipyramids, edges with two equivalent Mg(2)S6 octahedra, and edges with four equivalent Pr(2)S6 octahedra. There are four inequivalent Pr sites. In the first Pr site, Pr(1) is bonded to one S(1), one S(3), one S(4), one S(5), and one S(6) atom to form distorted PrS5 trigonal bipyramids that share  a cornercorner with one Pr(2)S6 octahedra, corners with two equivalent Mg(2)S6 octahedra, corners with three equivalent Mg(1)S4 tetrahedra, corners with two equivalent Pr(4)S5 trigonal bipyramids, and  an edgeedge with one Pr(4)S5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 62-65°. In the second Pr site, Pr(2) is bonded to one S(1), one S(8), two equivalent S(2), and two equivalent S(7) atoms to form distorted PrS6 octahedra that share corners with two equivalent Mg(1)S4 tetrahedra,  a cornercorner with one Pr(1)S5 trigonal bipyramid, corners with two equivalent Pr(4)S5 trigonal bipyramids, edges with two equivalent Pr(2)S6 octahedra, and edges with four equivalent Mg(2)S6 octahedra. In the third Pr site, Pr(3) is bonded in a 5-coordinate geometry to one S(3), one S(4), one S(8), and two equivalent S(6) atoms. In the fourth Pr site, Pr(4) is bonded to one S(3), one S(4), one S(7), and two equivalent S(5) atoms to form distorted PrS5 trigonal bipyramids that share  a cornercorner with one Mg(2)S6 octahedra, corners with two equivalent Pr(2)S6 octahedra, corners with three equivalent Mg(1)S4 tetrahedra, corners with two equivalent Pr(1)S5 trigonal bipyramids,  an edgeedge with one Pr(1)S5 trigonal bipyramid, and  an edgeedge with one Pr(4)S5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 60-65°. There are eight inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Mg(2), one Pr(1), and one Pr(2) atom to form SPr2Mg2 tetrahedra that share  a cornercorner with one S(3)Pr3Mg tetrahedra,  a cornercorner with one S(5)Pr3Mg tetrahedra,  a cornercorner with one S(6)Pr3Mg tetrahedra, corners with two equivalent S(2)Pr2Mg2 tetrahedra, corners with three equivalent S(8)Pr2Mg2 tetrahedra, corners with four equivalent S(7)Pr3Mg tetrahedra,  an edgeedge with one S(1)Pr2Mg2 tetrahedra,  an edgeedge with one S(2)Pr2Mg2 tetrahedra, and  an edgeedge with one S(8)Pr2Mg2 tetrahedra. In the second S site, S(2) is bonded to one Mg(1), one Mg(2), and two equivalent Pr(2) atoms to form SPr2Mg2 tetrahedra that share  a cornercorner with one S(3)Pr3Mg tetrahedra,  a cornercorner with one S(5)Pr3Mg tetrahedra,  a cornercorner with one S(6)Pr3Mg tetrahedra, corners with two equivalent S(1)Pr2Mg2 tetrahedra, corners with three equivalent S(7)Pr3Mg tetrahedra, corners with four equivalent S(8)Pr2Mg2 tetrahedra,  an edgeedge with one S(1)Pr2Mg2 tetrahedra,  an edgeedge with one S(2)Pr2Mg2 tetrahedra, and  an edgeedge with one S(7)Pr3Mg tetrahedra. In the third S site, S(3) is bonded to one Mg(1), one Pr(1), one Pr(3), and one Pr(4) atom to form distorted SPr3Mg tetrahedra that share  a cornercorner with one S(1)Pr2Mg2 tetrahedra,  a cornercorner with one S(2)Pr2Mg2 tetrahedra,  a cornercorner with one S(8)Pr2Mg2 tetrahedra,  a cornercorner with one S(7)Pr3Mg tetrahedra, corners with two equivalent S(5)Pr3Mg tetrahedra, corners with two equivalent S(6)Pr3Mg tetrahedra,  an edgeedge with one S(5)Pr3Mg tetrahedra, and  an edgeedge with one S(6)Pr3Mg tetrahedra. In the fourth S site, S(4) is bonded in a trigonal planar geometry to one Pr(1), one Pr(3), and one Pr(4) atom. In the fifth S site, S(5) is bonded to one Mg(1), one Pr(1), and two equivalent Pr(4) atoms to form distorted SPr3Mg tetrahedra that share  a cornercorner with one S(1)Pr2Mg2 tetrahedra,  a cornercorner with one S(2)Pr2Mg2 tetrahedra, corners with two equivalent S(3)Pr3Mg tetrahedra, corners with two equivalent S(6)Pr3Mg tetrahedra, corners with two equivalent S(7)Pr3Mg tetrahedra,  an edgeedge with one S(3)Pr3Mg tetrahedra, and  an edgeedge with one S(5)Pr3Mg tetrahedra. In the sixth S site, S(6) is bonded to one Mg(1), one Pr(1), and two equivalent Pr(3) atoms to form distorted SPr3Mg tetrahedra that share  a cornercorner with one S(1)Pr2Mg2 tetrahedra,  a cornercorner with one S(2)Pr2Mg2 tetrahedra, corners with two equivalent S(8)Pr2Mg2 tetrahedra, corners with two equivalent S(3)Pr3Mg tetrahedra, corners with two equivalent S(5)Pr3Mg tetrahedra,  an edgeedge with one S(3)Pr3Mg tetrahedra, and  an edgeedge with one S(6)Pr3Mg tetrahedra. In the seventh S site, S(7) is bonded to one Mg(2), one Pr(4), and two equivalent Pr(2) atoms to form distorted SPr3Mg tetrahedra that share  a cornercorner with one S(3)Pr3Mg tetrahedra, corners with two equivalent S(8)Pr2Mg2 tetrahedra, corners with two equivalent S(5)Pr3Mg tetrahedra, corners with three equivalent S(2)Pr2Mg2 tetrahedra, corners with four equivalent S(1)Pr2Mg2 tetrahedra,  an edgeedge with one S(2)Pr2Mg2 tetrahedra,  an edgeedge with one S(8)Pr2Mg2 tetrahedra, and  an edgeedge with one S(7)Pr3Mg tetrahedra. In the eighth S site, S(8) is bonded to two equivalent Mg(2), one Pr(2), and one Pr(3) atom to form SPr2Mg2 tetrahedra that share  a cornercorner with one S(3)Pr3Mg tetrahedra, corners with two equivalent S(6)Pr3Mg tetrahedra, corners with two equivalent S(7)Pr3Mg tetrahedra, corners with three equivalent S(1)Pr2Mg2 tetrahedra, corners with four equivalent S(2)Pr2Mg2 tetrahedra,  an edgeedge with one S(1)Pr2Mg2 tetrahedra,  an edgeedge with one S(8)Pr2Mg2 tetrahedra, and  an edgeedge with one S(7)Pr3Mg tetrahedra.
MgPr2S4 is Aluminum carbonitride-like structured and crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one S(2), one S(3), one S(5), and one S(6) atom to form MgS4 tetrahedra that share  a cornercorner with one Mg(2)S6 octahedra, corners with two equivalent Pr(2)S6 octahedra, corners with three equivalent Pr(1)S5 trigonal bipyramids, and corners with three equivalent Pr(4)S5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 61-66°. The Mg(1)-S(2) bond length is 2.42 Å. The Mg(1)-S(3) bond length is 2.49 Å. The Mg(1)-S(5) bond length is 2.52 Å. The Mg(1)-S(6) bond length is 2.49 Å. In the second Mg site, Mg(2) is bonded to one S(2), one S(7), two equivalent S(1), and two equivalent S(8) atoms to form distorted MgS6 octahedra that share  a cornercorner with one Mg(1)S4 tetrahedra,  a cornercorner with one Pr(4)S5 trigonal bipyramid, corners with two equivalent Pr(1)S5 trigonal bipyramids, edges with two equivalent Mg(2)S6 octahedra, and edges with four equivalent Pr(2)S6 octahedra. The Mg(2)-S(2) bond length is 2.75 Å. The Mg(2)-S(7) bond length is 3.05 Å. There is one shorter (2.73 Å) and one longer (2.85 Å) Mg(2)-S(1) bond length. There is one shorter (2.75 Å) and one longer (2.76 Å) Mg(2)-S(8) bond length. There are four inequivalent Pr sites. In the first Pr site, Pr(1) is bonded to one S(1), one S(3), one S(4), one S(5), and one S(6) atom to form distorted PrS5 trigonal bipyramids that share  a cornercorner with one Pr(2)S6 octahedra, corners with two equivalent Mg(2)S6 octahedra, corners with three equivalent Mg(1)S4 tetrahedra, corners with two equivalent Pr(4)S5 trigonal bipyramids, and  an edgeedge with one Pr(4)S5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 62-65°. The Pr(1)-S(1) bond length is 2.70 Å. The Pr(1)-S(3) bond length is 3.14 Å. The Pr(1)-S(4) bond length is 2.68 Å. The Pr(1)-S(5) bond length is 2.77 Å. The Pr(1)-S(6) bond length is 2.75 Å. In the second Pr site, Pr(2) is bonded to one S(1), one S(8), two equivalent S(2), and two equivalent S(7) atoms to form distorted PrS6 octahedra that share corners with two equivalent Mg(1)S4 tetrahedra,  a cornercorner with one Pr(1)S5 trigonal bipyramid, corners with two equivalent Pr(4)S5 trigonal bipyramids, edges with two equivalent Pr(2)S6 octahedra, and edges with four equivalent Mg(2)S6 octahedra. The Pr(2)-S(1) bond length is 2.90 Å. The Pr(2)-S(8) bond length is 2.96 Å. There is one shorter (2.93 Å) and one longer (2.98 Å) Pr(2)-S(2) bond length. Both Pr(2)-S(7) bond lengths are 2.92 Å. In the third Pr site, Pr(3) is bonded in a 5-coordinate geometry to one S(3), one S(4), one S(8), and two equivalent S(6) atoms. The Pr(3)-S(3) bond length is 2.74 Å. The Pr(3)-S(4) bond length is 2.67 Å. The Pr(3)-S(8) bond length is 2.71 Å. There is one shorter (2.73 Å) and one longer (3.15 Å) Pr(3)-S(6) bond length. In the fourth Pr site, Pr(4) is bonded to one S(3), one S(4), one S(7), and two equivalent S(5) atoms to form distorted PrS5 trigonal bipyramids that share  a cornercorner with one Mg(2)S6 octahedra, corners with two equivalent Pr(2)S6 octahedra, corners with three equivalent Mg(1)S4 tetrahedra, corners with two equivalent Pr(1)S5 trigonal bipyramids,  an edgeedge with one Pr(1)S5 trigonal bipyramid, and  an edgeedge with one Pr(4)S5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 60-65°. The Pr(4)-S(3) bond length is 2.72 Å. The Pr(4)-S(4) bond length is 2.66 Å. The Pr(4)-S(7) bond length is 2.70 Å. There is one shorter (2.75 Å) and one longer (3.13 Å) Pr(4)-S(5) bond length. There are eight inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Mg(2), one Pr(1), and one Pr(2) atom to form SPr2Mg2 tetrahedra that share  a cornercorner with one S(3)Pr3Mg tetrahedra,  a cornercorner with one S(5)Pr3Mg tetrahedra,  a cornercorner with one S(6)Pr3Mg tetrahedra, corners with two equivalent S(2)Pr2Mg2 tetrahedra, corners with three equivalent S(8)Pr2Mg2 tetrahedra, corners with four equivalent S(7)Pr3Mg tetrahedra,  an edgeedge with one S(1)Pr2Mg2 tetrahedra,  an edgeedge with one S(2)Pr2Mg2 tetrahedra, and  an edgeedge with one S(8)Pr2Mg2 tetrahedra. In the second S site, S(2) is bonded to one Mg(1), one Mg(2), and two equivalent Pr(2) atoms to form SPr2Mg2 tetrahedra that share  a cornercorner with one S(3)Pr3Mg tetrahedra,  a cornercorner with one S(5)Pr3Mg tetrahedra,  a cornercorner with one S(6)Pr3Mg tetrahedra, corners with two equivalent S(1)Pr2Mg2 tetrahedra, corners with three equivalent S(7)Pr3Mg tetrahedra, corners with four equivalent S(8)Pr2Mg2 tetrahedra,  an edgeedge with one S(1)Pr2Mg2 tetrahedra,  an edgeedge with one S(2)Pr2Mg2 tetrahedra, and  an edgeedge with one S(7)Pr3Mg tetrahedra. In the third S site, S(3) is bonded to one Mg(1), one Pr(1), one Pr(3), and one Pr(4) atom to form distorted SPr3Mg tetrahedra that share  a cornercorner with one S(1)Pr2Mg2 tetrahedra,  a cornercorner with one S(2)Pr2Mg2 tetrahedra,  a cornercorner with one S(8)Pr2Mg2 tetrahedra,  a cornercorner with one S(7)Pr3Mg tetrahedra, corners with two equivalent S(5)Pr3Mg tetrahedra, corners with two equivalent S(6)Pr3Mg tetrahedra,  an edgeedge with one S(5)Pr3Mg tetrahedra, and  an edgeedge with one S(6)Pr3Mg tetrahedra. In the fourth S site, S(4) is bonded in a trigonal planar geometry to one Pr(1), one Pr(3), and one Pr(4) atom. In the fifth S site, S(5) is bonded to one Mg(1), one Pr(1), and two equivalent Pr(4) atoms to form distorted SPr3Mg tetrahedra that share  a cornercorner with one S(1)Pr2Mg2 tetrahedra,  a cornercorner with one S(2)Pr2Mg2 tetrahedra, corners with two equivalent S(3)Pr3Mg tetrahedra, corners with two equivalent S(6)Pr3Mg tetrahedra, corners with two equivalent S(7)Pr3Mg tetrahedra,  an edgeedge with one S(3)Pr3Mg tetrahedra, and  an edgeedge with one S(5)Pr3Mg tetrahedra. In the sixth S site, S(6) is bonded to one Mg(1), one Pr(1), and two equivalent Pr(3) atoms to form distorted SPr3Mg tetrahedra that share  a cornercorner with one S(1)Pr2Mg2 tetrahedra,  a cornercorner with one S(2)Pr2Mg2 tetrahedra, corners with two equivalent S(8)Pr2Mg2 tetrahedra, corners with two equivalent S(3)Pr3Mg tetrahedra, corners with two equivalent S(5)Pr3Mg tetrahedra,  an edgeedge with one S(3)Pr3Mg tetrahedra, and  an edgeedge with one S(6)Pr3Mg tetrahedra. In the seventh S site, S(7) is bonded to one Mg(2), one Pr(4), and two equivalent Pr(2) atoms to form distorted SPr3Mg tetrahedra that share  a cornercorner with one S(3)Pr3Mg tetrahedra, corners with two equivalent S(8)Pr2Mg2 tetrahedra, corners with two equivalent S(5)Pr3Mg tetrahedra, corners with three equivalent S(2)Pr2Mg2 tetrahedra, corners with four equivalent S(1)Pr2Mg2 tetrahedra,  an edgeedge with one S(2)Pr2Mg2 tetrahedra,  an edgeedge with one S(8)Pr2Mg2 tetrahedra, and  an edgeedge with one S(7)Pr3Mg tetrahedra. In the eighth S site, S(8) is bonded to two equivalent Mg(2), one Pr(2), and one Pr(3) atom to form SPr2Mg2 tetrahedra that share  a cornercorner with one S(3)Pr3Mg tetrahedra, corners with two equivalent S(6)Pr3Mg tetrahedra, corners with two equivalent S(7)Pr3Mg tetrahedra, corners with three equivalent S(1)Pr2Mg2 tetrahedra, corners with four equivalent S(2)Pr2Mg2 tetrahedra,  an edgeedge with one S(1)Pr2Mg2 tetrahedra,  an edgeedge with one S(8)Pr2Mg2 tetrahedra, and  an edgeedge with one S(7)Pr3Mg tetrahedra.