Na2(ReSe2)3 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent Se(3), two equivalent Se(4), and two equivalent Se(6) atoms. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to two equivalent Se(1), two equivalent Se(4), two equivalent Se(5), and two equivalent Se(6) atoms. In the third Na site, Na(3) is bonded in a 5-coordinate geometry to one Se(3), one Se(4), one Se(5), one Se(6), and two equivalent Se(2) atoms. There are three inequivalent Re sites. In the first Re site, Re(1) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), and one Se(5) atom to form distorted edge-sharing ReSe5 square pyramids. In the second Re site, Re(2) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), and one Se(6) atom to form a mixture of distorted edge and corner-sharing ReSe5 square pyramids. In the third Re site, Re(3) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), and one Se(6) atom to form a mixture of distorted edge and corner-sharing ReSe5 square pyramids. There are six inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one Na(2), one Re(1), one Re(2), and one Re(3) atom. In the second Se site, Se(2) is bonded to two equivalent Na(3), one Re(1), one Re(2), and one Re(3) atom to form distorted SeNa2Re3 trigonal bipyramids that share corners with two equivalent Se(6)Na3Re2 trigonal bipyramids,  an edgeedge with one Se(2)Na2Re3 trigonal bipyramid, and  an edgeedge with one Se(6)Na3Re2 trigonal bipyramid. In the third Se site, Se(3) is bonded in a distorted pentagonal planar geometry to one Na(1), one Na(3), one Re(1), one Re(2), and one Re(3) atom. In the fourth Se site, Se(4) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(3), one Re(1), one Re(2), and one Re(3) atom. In the fifth Se site, Se(5) is bonded in a 4-coordinate geometry to one Na(2), one Na(3), one Re(1), and one Se(5) atom. In the sixth Se site, Se(6) is bonded to one Na(1), one Na(2), one Na(3), one Re(2), and one Re(3) atom to form distorted SeNa3Re2 trigonal bipyramids that share corners with two equivalent Se(2)Na2Re3 trigonal bipyramids,  an edgeedge with one Se(2)Na2Re3 trigonal bipyramid, and  an edgeedge with one Se(6)Na3Re2 trigonal bipyramid.
Na2(ReSe2)3 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent Se(3), two equivalent Se(4), and two equivalent Se(6) atoms. Both Na(1)-Se(3) bond lengths are 3.40 Å. Both Na(1)-Se(4) bond lengths are 3.52 Å. Both Na(1)-Se(6) bond lengths are 2.94 Å. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to two equivalent Se(1), two equivalent Se(4), two equivalent Se(5), and two equivalent Se(6) atoms. Both Na(2)-Se(1) bond lengths are 3.25 Å. Both Na(2)-Se(4) bond lengths are 3.47 Å. Both Na(2)-Se(5) bond lengths are 3.10 Å. Both Na(2)-Se(6) bond lengths are 3.08 Å. In the third Na site, Na(3) is bonded in a 5-coordinate geometry to one Se(3), one Se(4), one Se(5), one Se(6), and two equivalent Se(2) atoms. The Na(3)-Se(3) bond length is 3.26 Å. The Na(3)-Se(4) bond length is 3.54 Å. The Na(3)-Se(5) bond length is 3.04 Å. The Na(3)-Se(6) bond length is 3.05 Å. There is one shorter (3.05 Å) and one longer (3.23 Å) Na(3)-Se(2) bond length. There are three inequivalent Re sites. In the first Re site, Re(1) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), and one Se(5) atom to form distorted edge-sharing ReSe5 square pyramids. The Re(1)-Se(1) bond length is 2.53 Å. The Re(1)-Se(2) bond length is 2.57 Å. The Re(1)-Se(3) bond length is 2.55 Å. The Re(1)-Se(4) bond length is 2.56 Å. The Re(1)-Se(5) bond length is 2.58 Å. In the second Re site, Re(2) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), and one Se(6) atom to form a mixture of distorted edge and corner-sharing ReSe5 square pyramids. The Re(2)-Se(1) bond length is 2.54 Å. The Re(2)-Se(2) bond length is 2.54 Å. The Re(2)-Se(3) bond length is 2.56 Å. The Re(2)-Se(4) bond length is 2.57 Å. The Re(2)-Se(6) bond length is 2.67 Å. In the third Re site, Re(3) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), and one Se(6) atom to form a mixture of distorted edge and corner-sharing ReSe5 square pyramids. The Re(3)-Se(1) bond length is 2.53 Å. The Re(3)-Se(2) bond length is 2.55 Å. The Re(3)-Se(3) bond length is 2.54 Å. The Re(3)-Se(4) bond length is 2.57 Å. The Re(3)-Se(6) bond length is 2.69 Å. There are six inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one Na(2), one Re(1), one Re(2), and one Re(3) atom. In the second Se site, Se(2) is bonded to two equivalent Na(3), one Re(1), one Re(2), and one Re(3) atom to form distorted SeNa2Re3 trigonal bipyramids that share corners with two equivalent Se(6)Na3Re2 trigonal bipyramids,  an edgeedge with one Se(2)Na2Re3 trigonal bipyramid, and  an edgeedge with one Se(6)Na3Re2 trigonal bipyramid. In the third Se site, Se(3) is bonded in a distorted pentagonal planar geometry to one Na(1), one Na(3), one Re(1), one Re(2), and one Re(3) atom. In the fourth Se site, Se(4) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(3), one Re(1), one Re(2), and one Re(3) atom. In the fifth Se site, Se(5) is bonded in a 4-coordinate geometry to one Na(2), one Na(3), one Re(1), and one Se(5) atom. The Se(5)-Se(5) bond length is 2.43 Å. In the sixth Se site, Se(6) is bonded to one Na(1), one Na(2), one Na(3), one Re(2), and one Re(3) atom to form distorted SeNa3Re2 trigonal bipyramids that share corners with two equivalent Se(2)Na2Re3 trigonal bipyramids,  an edgeedge with one Se(2)Na2Re3 trigonal bipyramid, and  an edgeedge with one Se(6)Na3Re2 trigonal bipyramid.