Rb2Nb2P2S11 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 9-coordinate geometry to one S(8), four equivalent S(3), and four equivalent S(5) atoms. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one S(6), one S(7), two equivalent S(9), and four equivalent S(2) atoms. Nb(1) is bonded in a 7-coordinate geometry to one S(1), one S(3), one S(4), one S(6), one S(7), one S(8), and one S(9) atom. There are two inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one S(5), one S(8), and two equivalent S(3) atoms. In the second P site, P(2) is bonded in a tetrahedral geometry to one S(2), one S(7), and two equivalent S(9) atoms. There are nine inequivalent S sites. In the first S site, S(1) is bonded in a 3-coordinate geometry to two equivalent Nb(1) and one S(6) atom. In the second S site, S(2) is bonded to four equivalent Rb(2) and one P(2) atom to form distorted SRb4P square pyramids that share corners with four equivalent S(2)Rb4P square pyramids, corners with three equivalent S(7)RbNb2P trigonal pyramids, edges with four equivalent S(2)Rb4P square pyramids, and  an edgeedge with one S(7)RbNb2P trigonal pyramid. In the third S site, S(3) is bonded in a distorted L-shaped geometry to two equivalent Rb(1), one Nb(1), and one P(1) atom. In the fourth S site, S(4) is bonded in a 2-coordinate geometry to two equivalent Nb(1) atoms. In the fifth S site, S(5) is bonded in a 5-coordinate geometry to four equivalent Rb(1) and one P(1) atom. In the sixth S site, S(6) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Nb(1), and one S(1) atom. In the seventh S site, S(7) is bonded to one Rb(2), two equivalent Nb(1), and one P(2) atom to form distorted SRbNb2P trigonal pyramids that share corners with three equivalent S(2)Rb4P square pyramids,  an edgeedge with one S(2)Rb4P square pyramid, and  an edgeedge with one S(8)RbNb2P trigonal pyramid. In the eighth S site, S(8) is bonded to one Rb(1), two equivalent Nb(1), and one P(1) atom to form distorted edge-sharing SRbNb2P trigonal pyramids. In the ninth S site, S(9) is bonded in a distorted L-shaped geometry to one Rb(2), one Nb(1), and one P(2) atom.
Rb2Nb2P2S11 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 9-coordinate geometry to one S(8), four equivalent S(3), and four equivalent S(5) atoms. The Rb(1)-S(8) bond length is 3.81 Å. There are two shorter (3.57 Å) and two longer (3.83 Å) Rb(1)-S(3) bond lengths. There are a spread of Rb(1)-S(5) bond distances ranging from 3.44-3.69 Å. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one S(6), one S(7), two equivalent S(9), and four equivalent S(2) atoms. The Rb(2)-S(6) bond length is 3.60 Å. The Rb(2)-S(7) bond length is 3.62 Å. Both Rb(2)-S(9) bond lengths are 3.84 Å. There are a spread of Rb(2)-S(2) bond distances ranging from 3.54-3.62 Å. Nb(1) is bonded in a 7-coordinate geometry to one S(1), one S(3), one S(4), one S(6), one S(7), one S(8), and one S(9) atom. The Nb(1)-S(1) bond length is 2.54 Å. The Nb(1)-S(3) bond length is 2.51 Å. The Nb(1)-S(4) bond length is 2.36 Å. The Nb(1)-S(6) bond length is 2.48 Å. The Nb(1)-S(7) bond length is 2.74 Å. The Nb(1)-S(8) bond length is 2.77 Å. The Nb(1)-S(9) bond length is 2.61 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one S(5), one S(8), and two equivalent S(3) atoms. The P(1)-S(5) bond length is 1.99 Å. The P(1)-S(8) bond length is 2.07 Å. Both P(1)-S(3) bond lengths are 2.07 Å. In the second P site, P(2) is bonded in a tetrahedral geometry to one S(2), one S(7), and two equivalent S(9) atoms. The P(2)-S(2) bond length is 2.01 Å. The P(2)-S(7) bond length is 2.11 Å. Both P(2)-S(9) bond lengths are 2.06 Å. There are nine inequivalent S sites. In the first S site, S(1) is bonded in a 3-coordinate geometry to two equivalent Nb(1) and one S(6) atom. The S(1)-S(6) bond length is 2.01 Å. In the second S site, S(2) is bonded to four equivalent Rb(2) and one P(2) atom to form distorted SRb4P square pyramids that share corners with four equivalent S(2)Rb4P square pyramids, corners with three equivalent S(7)RbNb2P trigonal pyramids, edges with four equivalent S(2)Rb4P square pyramids, and  an edgeedge with one S(7)RbNb2P trigonal pyramid. In the third S site, S(3) is bonded in a distorted L-shaped geometry to two equivalent Rb(1), one Nb(1), and one P(1) atom. In the fourth S site, S(4) is bonded in a 2-coordinate geometry to two equivalent Nb(1) atoms. In the fifth S site, S(5) is bonded in a 5-coordinate geometry to four equivalent Rb(1) and one P(1) atom. In the sixth S site, S(6) is bonded in a 4-coordinate geometry to one Rb(2), two equivalent Nb(1), and one S(1) atom. In the seventh S site, S(7) is bonded to one Rb(2), two equivalent Nb(1), and one P(2) atom to form distorted SRbNb2P trigonal pyramids that share corners with three equivalent S(2)Rb4P square pyramids,  an edgeedge with one S(2)Rb4P square pyramid, and  an edgeedge with one S(8)RbNb2P trigonal pyramid. In the eighth S site, S(8) is bonded to one Rb(1), two equivalent Nb(1), and one P(1) atom to form distorted edge-sharing SRbNb2P trigonal pyramids. In the ninth S site, S(9) is bonded in a distorted L-shaped geometry to one Rb(2), one Nb(1), and one P(2) atom.