K3Np3Si2O13 crystallizes in the triclinic P1 space group. There are three inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one O(11), one O(8), two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms. In the second K site, K(2) is bonded in a 8-coordinate geometry to one O(10), one O(9), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the third K site, K(3) is bonded in a 8-coordinate geometry to one O(12), one O(7), two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms. There are three inequivalent Np sites. In the first Np site, Np(1) is bonded in a 7-coordinate geometry to one O(1), one O(13), one O(4), two equivalent O(11), and two equivalent O(7) atoms. In the second Np site, Np(2) is bonded in a 7-coordinate geometry to one O(13), one O(2), one O(5), two equivalent O(10), and two equivalent O(8) atoms. In the third Np site, Np(3) is bonded in a 7-coordinate geometry to one O(13), one O(3), one O(6), two equivalent O(12), and two equivalent O(9) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a trigonal planar geometry to one O(7), one O(8), and one O(9) atom. In the second Si site, Si(2) is bonded to one O(10), one O(11), one O(12), and two equivalent O(13) atoms to form distorted corner-sharing SiO5 trigonal bipyramids. There are thirteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(3), and one Np(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), and one Np(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to two equivalent K(2), two equivalent K(3), and one Np(3) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent K(2) and one Np(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent K(3) and one Np(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent K(1) and one Np(3) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one K(3), two equivalent Np(1), and one Si(1) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(1), two equivalent Np(2), and one Si(1) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one K(2), two equivalent Np(3), and one Si(1) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one K(2), two equivalent Np(2), and one Si(2) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one K(1), two equivalent Np(1), and one Si(2) atom. In the twelfth O site, O(12) is bonded in a 4-coordinate geometry to one K(3), two equivalent Np(3), and one Si(2) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one Np(1), one Np(2), one Np(3), and two equivalent Si(2) atoms.
K3Np3Si2O13 crystallizes in the triclinic P1 space group. There are three inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one O(11), one O(8), two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms. The K(1)-O(11) bond length is 3.04 Å. The K(1)-O(8) bond length is 2.96 Å. There is one shorter (2.85 Å) and one longer (2.86 Å) K(1)-O(1) bond length. There is one shorter (3.02 Å) and one longer (3.03 Å) K(1)-O(2) bond length. Both K(1)-O(6) bond lengths are 2.65 Å. In the second K site, K(2) is bonded in a 8-coordinate geometry to one O(10), one O(9), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. The K(2)-O(10) bond length is 3.03 Å. The K(2)-O(9) bond length is 2.98 Å. There is one shorter (2.85 Å) and one longer (2.86 Å) K(2)-O(2) bond length. There is one shorter (3.02 Å) and one longer (3.03 Å) K(2)-O(3) bond length. Both K(2)-O(4) bond lengths are 2.64 Å. In the third K site, K(3) is bonded in a 8-coordinate geometry to one O(12), one O(7), two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms. The K(3)-O(12) bond length is 3.04 Å. The K(3)-O(7) bond length is 2.97 Å. There is one shorter (3.03 Å) and one longer (3.04 Å) K(3)-O(1) bond length. There is one shorter (2.85 Å) and one longer (2.86 Å) K(3)-O(3) bond length. Both K(3)-O(5) bond lengths are 2.64 Å. There are three inequivalent Np sites. In the first Np site, Np(1) is bonded in a 7-coordinate geometry to one O(1), one O(13), one O(4), two equivalent O(11), and two equivalent O(7) atoms. The Np(1)-O(1) bond length is 1.88 Å. The Np(1)-O(13) bond length is 2.80 Å. The Np(1)-O(4) bond length is 1.85 Å. There is one shorter (2.32 Å) and one longer (2.36 Å) Np(1)-O(11) bond length. There is one shorter (2.57 Å) and one longer (2.59 Å) Np(1)-O(7) bond length. In the second Np site, Np(2) is bonded in a 7-coordinate geometry to one O(13), one O(2), one O(5), two equivalent O(10), and two equivalent O(8) atoms. The Np(2)-O(13) bond length is 2.80 Å. The Np(2)-O(2) bond length is 1.88 Å. The Np(2)-O(5) bond length is 1.85 Å. There is one shorter (2.32 Å) and one longer (2.36 Å) Np(2)-O(10) bond length. There is one shorter (2.57 Å) and one longer (2.59 Å) Np(2)-O(8) bond length. In the third Np site, Np(3) is bonded in a 7-coordinate geometry to one O(13), one O(3), one O(6), two equivalent O(12), and two equivalent O(9) atoms. The Np(3)-O(13) bond length is 2.79 Å. The Np(3)-O(3) bond length is 1.88 Å. The Np(3)-O(6) bond length is 1.85 Å. There is one shorter (2.31 Å) and one longer (2.36 Å) Np(3)-O(12) bond length. There is one shorter (2.56 Å) and one longer (2.59 Å) Np(3)-O(9) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a trigonal planar geometry to one O(7), one O(8), and one O(9) atom. The Si(1)-O(7) bond length is 1.60 Å. The Si(1)-O(8) bond length is 1.60 Å. The Si(1)-O(9) bond length is 1.60 Å. In the second Si site, Si(2) is bonded to one O(10), one O(11), one O(12), and two equivalent O(13) atoms to form distorted corner-sharing SiO5 trigonal bipyramids. The Si(2)-O(10) bond length is 1.67 Å. The Si(2)-O(11) bond length is 1.67 Å. The Si(2)-O(12) bond length is 1.67 Å. There is one shorter (1.68 Å) and one longer (2.28 Å) Si(2)-O(13) bond length. There are thirteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(3), and one Np(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), and one Np(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to two equivalent K(2), two equivalent K(3), and one Np(3) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent K(2) and one Np(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent K(3) and one Np(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent K(1) and one Np(3) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one K(3), two equivalent Np(1), and one Si(1) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(1), two equivalent Np(2), and one Si(1) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one K(2), two equivalent Np(3), and one Si(1) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one K(2), two equivalent Np(2), and one Si(2) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one K(1), two equivalent Np(1), and one Si(2) atom. In the twelfth O site, O(12) is bonded in a 4-coordinate geometry to one K(3), two equivalent Np(3), and one Si(2) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one Np(1), one Np(2), one Np(3), and two equivalent Si(2) atoms.