K4MgNb2(AgS4)2 crystallizes in the monoclinic C2 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to two equivalent S(1), two equivalent S(2), and two equivalent S(4) atoms. In the second K site, K(2) is bonded in a 6-coordinate geometry to two equivalent S(2), two equivalent S(3), and two equivalent S(4) atoms. In the third K site, K(3) is bonded in a 8-coordinate geometry to two equivalent S(2), two equivalent S(3), and four equivalent S(1) atoms. In the fourth K site, K(4) is bonded in a 6-coordinate geometry to two equivalent S(1) and four equivalent S(3) atoms. Mg(1) is bonded in a 4-coordinate geometry to two equivalent S(2) and two equivalent S(4) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a tetrahedral geometry to two equivalent S(3) and two equivalent S(4) atoms. In the second Nb site, Nb(2) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form NbS4 tetrahedra that share edges with two equivalent Ag(2)S4 tetrahedra. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded in a 4-coordinate geometry to two equivalent S(3) and two equivalent S(4) atoms. In the second Ag site, Ag(2) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form distorted AgS4 tetrahedra that share edges with two equivalent Nb(2)S4 tetrahedra. There are four inequivalent S sites. In the first S site, S(1) is bonded in a 6-coordinate geometry to one K(1), one K(4), two equivalent K(3), one Nb(2), and one Ag(2) atom. In the second S site, S(2) is bonded in a 6-coordinate geometry to one K(1), one K(2), one K(3), one Mg(1), one Nb(2), and one Ag(2) atom. In the third S site, S(3) is bonded in a 6-coordinate geometry to one K(2), one K(3), two equivalent K(4), one Nb(1), and one Ag(1) atom. In the fourth S site, S(4) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Mg(1), one Nb(1), and one Ag(1) atom.
K4MgNb2(AgS4)2 crystallizes in the monoclinic C2 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to two equivalent S(1), two equivalent S(2), and two equivalent S(4) atoms. Both K(1)-S(1) bond lengths are 3.23 Å. Both K(1)-S(2) bond lengths are 3.25 Å. Both K(1)-S(4) bond lengths are 3.59 Å. In the second K site, K(2) is bonded in a 6-coordinate geometry to two equivalent S(2), two equivalent S(3), and two equivalent S(4) atoms. Both K(2)-S(2) bond lengths are 3.37 Å. Both K(2)-S(3) bond lengths are 3.50 Å. Both K(2)-S(4) bond lengths are 3.48 Å. In the third K site, K(3) is bonded in a 8-coordinate geometry to two equivalent S(2), two equivalent S(3), and four equivalent S(1) atoms. Both K(3)-S(2) bond lengths are 3.68 Å. Both K(3)-S(3) bond lengths are 3.42 Å. There are two shorter (3.59 Å) and two longer (3.65 Å) K(3)-S(1) bond lengths. In the fourth K site, K(4) is bonded in a 6-coordinate geometry to two equivalent S(1) and four equivalent S(3) atoms. Both K(4)-S(1) bond lengths are 3.39 Å. There are two shorter (3.51 Å) and two longer (3.67 Å) K(4)-S(3) bond lengths. Mg(1) is bonded in a 4-coordinate geometry to two equivalent S(2) and two equivalent S(4) atoms. Both Mg(1)-S(2) bond lengths are 2.48 Å. Both Mg(1)-S(4) bond lengths are 2.45 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a tetrahedral geometry to two equivalent S(3) and two equivalent S(4) atoms. Both Nb(1)-S(3) bond lengths are 2.32 Å. Both Nb(1)-S(4) bond lengths are 2.39 Å. In the second Nb site, Nb(2) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form NbS4 tetrahedra that share edges with two equivalent Ag(2)S4 tetrahedra. Both Nb(2)-S(1) bond lengths are 2.32 Å. Both Nb(2)-S(2) bond lengths are 2.40 Å. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded in a 4-coordinate geometry to two equivalent S(3) and two equivalent S(4) atoms. Both Ag(1)-S(3) bond lengths are 2.52 Å. Both Ag(1)-S(4) bond lengths are 2.74 Å. In the second Ag site, Ag(2) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form distorted AgS4 tetrahedra that share edges with two equivalent Nb(2)S4 tetrahedra. Both Ag(2)-S(1) bond lengths are 2.58 Å. Both Ag(2)-S(2) bond lengths are 2.69 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded in a 6-coordinate geometry to one K(1), one K(4), two equivalent K(3), one Nb(2), and one Ag(2) atom. In the second S site, S(2) is bonded in a 6-coordinate geometry to one K(1), one K(2), one K(3), one Mg(1), one Nb(2), and one Ag(2) atom. In the third S site, S(3) is bonded in a 6-coordinate geometry to one K(2), one K(3), two equivalent K(4), one Nb(1), and one Ag(1) atom. In the fourth S site, S(4) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Mg(1), one Nb(1), and one Ag(1) atom.