USe2 crystallizes in the triclinic P1 space group. There are ten inequivalent U sites. In the first U site, U(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(10), one Se(13), one Se(16), one Se(18), one Se(20), one Se(5), and one Se(6) atom. In the second U site, U(2) is bonded in a 8-coordinate geometry to one Se(14), one Se(15), one Se(19), one Se(2), one Se(20), one Se(5), one Se(7), and one Se(9) atom. In the third U site, U(3) is bonded in a 8-coordinate geometry to one Se(11), one Se(15), one Se(17), one Se(18), one Se(3), one Se(6), one Se(8), and one Se(9) atom. In the fourth U site, U(4) is bonded in a 8-coordinate geometry to one Se(10), one Se(12), one Se(16), one Se(17), one Se(19), one Se(4), one Se(7), and one Se(8) atom. In the fifth U site, U(5) is bonded in a 8-coordinate geometry to one Se(1), one Se(2), one Se(3), one Se(4), one Se(5), one Se(6), one Se(7), and one Se(8) atom. In the sixth U site, U(6) is bonded in a 8-coordinate geometry to one Se(11), one Se(12), one Se(15), one Se(17), one Se(2), one Se(4), one Se(7), and one Se(9) atom. In the seventh U site, U(7) is bonded in a 8-coordinate geometry to one Se(10), one Se(11), one Se(13), one Se(16), one Se(18), one Se(3), one Se(4), and one Se(8) atom. In the eighth U site, U(8) is bonded in a 8-coordinate geometry to one Se(1), one Se(10), one Se(12), one Se(14), one Se(16), one Se(19), one Se(2), and one Se(5) atom. In the ninth U site, U(9) is bonded in a 8-coordinate geometry to one Se(1), one Se(13), one Se(14), one Se(15), one Se(20), one Se(3), one Se(6), and one Se(9) atom. In the tenth U site, U(10) is bonded in a 8-coordinate geometry to one Se(11), one Se(12), one Se(13), one Se(14), one Se(17), one Se(18), one Se(19), and one Se(20) atom. There are twenty inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted rectangular see-saw-like geometry to one U(1), one U(5), one U(8), and one U(9) atom. In the second Se site, Se(2) is bonded in a distorted rectangular see-saw-like geometry to one U(2), one U(5), one U(6), and one U(8) atom. In the third Se site, Se(3) is bonded in a distorted rectangular see-saw-like geometry to one U(3), one U(5), one U(7), and one U(9) atom. In the fourth Se site, Se(4) is bonded in a distorted rectangular see-saw-like geometry to one U(4), one U(5), one U(6), and one U(7) atom. In the fifth Se site, Se(5) is bonded to one U(1), one U(2), one U(5), and one U(8) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the sixth Se site, Se(6) is bonded to one U(1), one U(3), one U(5), and one U(9) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the seventh Se site, Se(7) is bonded to one U(2), one U(4), one U(5), and one U(6) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the eighth Se site, Se(8) is bonded to one U(3), one U(4), one U(5), and one U(7) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the ninth Se site, Se(9) is bonded to one U(2), one U(3), one U(6), and one U(9) atom to form a mixture of edge and corner-sharing SeU4 tetrahedra. In the tenth Se site, Se(10) is bonded to one U(1), one U(4), one U(7), and one U(8) atom to form a mixture of edge and corner-sharing SeU4 tetrahedra. In the eleventh Se site, Se(11) is bonded to one U(10), one U(3), one U(6), and one U(7) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the twelfth Se site, Se(12) is bonded to one U(10), one U(4), one U(6), and one U(8) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the thirteenth Se site, Se(13) is bonded to one U(1), one U(10), one U(7), and one U(9) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the fourteenth Se site, Se(14) is bonded to one U(10), one U(2), one U(8), and one U(9) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the fifteenth Se site, Se(15) is bonded to one U(2), one U(3), one U(6), and one U(9) atom to form a mixture of edge and corner-sharing SeU4 tetrahedra. In the sixteenth Se site, Se(16) is bonded to one U(1), one U(4), one U(7), and one U(8) atom to form a mixture of edge and corner-sharing SeU4 tetrahedra. In the seventeenth Se site, Se(17) is bonded in a distorted rectangular see-saw-like geometry to one U(10), one U(3), one U(4), and one U(6) atom. In the eighteenth Se site, Se(18) is bonded in a distorted rectangular see-saw-like geometry to one U(1), one U(10), one U(3), and one U(7) atom. In the nineteenth Se site, Se(19) is bonded in a distorted rectangular see-saw-like geometry to one U(10), one U(2), one U(4), and one U(8) atom. In the twentieth Se site, Se(20) is bonded in a distorted rectangular see-saw-like geometry to one U(1), one U(10), one U(2), and one U(9) atom.
USe2 crystallizes in the triclinic P1 space group. There are ten inequivalent U sites. In the first U site, U(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(10), one Se(13), one Se(16), one Se(18), one Se(20), one Se(5), and one Se(6) atom. The U(1)-Se(1) bond length is 2.92 Å. The U(1)-Se(10) bond length is 2.89 Å. The U(1)-Se(13) bond length is 2.90 Å. The U(1)-Se(16) bond length is 2.91 Å. The U(1)-Se(18) bond length is 3.20 Å. The U(1)-Se(20) bond length is 2.94 Å. The U(1)-Se(5) bond length is 3.11 Å. The U(1)-Se(6) bond length is 2.93 Å. In the second U site, U(2) is bonded in a 8-coordinate geometry to one Se(14), one Se(15), one Se(19), one Se(2), one Se(20), one Se(5), one Se(7), and one Se(9) atom. The U(2)-Se(14) bond length is 2.89 Å. The U(2)-Se(15) bond length is 2.91 Å. The U(2)-Se(19) bond length is 2.95 Å. The U(2)-Se(2) bond length is 2.92 Å. The U(2)-Se(20) bond length is 3.23 Å. The U(2)-Se(5) bond length is 2.93 Å. The U(2)-Se(7) bond length is 3.09 Å. The U(2)-Se(9) bond length is 2.89 Å. In the third U site, U(3) is bonded in a 8-coordinate geometry to one Se(11), one Se(15), one Se(17), one Se(18), one Se(3), one Se(6), one Se(8), and one Se(9) atom. The U(3)-Se(11) bond length is 2.89 Å. The U(3)-Se(15) bond length is 2.92 Å. The U(3)-Se(17) bond length is 3.24 Å. The U(3)-Se(18) bond length is 2.95 Å. The U(3)-Se(3) bond length is 2.92 Å. The U(3)-Se(6) bond length is 3.09 Å. The U(3)-Se(8) bond length is 2.93 Å. The U(3)-Se(9) bond length is 2.89 Å. In the fourth U site, U(4) is bonded in a 8-coordinate geometry to one Se(10), one Se(12), one Se(16), one Se(17), one Se(19), one Se(4), one Se(7), and one Se(8) atom. The U(4)-Se(10) bond length is 2.90 Å. The U(4)-Se(12) bond length is 2.91 Å. The U(4)-Se(16) bond length is 2.90 Å. The U(4)-Se(17) bond length is 2.93 Å. The U(4)-Se(19) bond length is 3.20 Å. The U(4)-Se(4) bond length is 2.91 Å. The U(4)-Se(7) bond length is 2.93 Å. The U(4)-Se(8) bond length is 3.12 Å. In the fifth U site, U(5) is bonded in a 8-coordinate geometry to one Se(1), one Se(2), one Se(3), one Se(4), one Se(5), one Se(6), one Se(7), and one Se(8) atom. The U(5)-Se(1) bond length is 2.91 Å. The U(5)-Se(2) bond length is 2.90 Å. The U(5)-Se(3) bond length is 2.89 Å. The U(5)-Se(4) bond length is 2.91 Å. The U(5)-Se(5) bond length is 2.96 Å. The U(5)-Se(6) bond length is 2.97 Å. The U(5)-Se(7) bond length is 2.98 Å. The U(5)-Se(8) bond length is 2.95 Å. In the sixth U site, U(6) is bonded in a 8-coordinate geometry to one Se(11), one Se(12), one Se(15), one Se(17), one Se(2), one Se(4), one Se(7), and one Se(9) atom. The U(6)-Se(11) bond length is 3.09 Å. The U(6)-Se(12) bond length is 2.93 Å. The U(6)-Se(15) bond length is 2.92 Å. The U(6)-Se(17) bond length is 2.92 Å. The U(6)-Se(2) bond length is 3.23 Å. The U(6)-Se(4) bond length is 2.95 Å. The U(6)-Se(7) bond length is 2.89 Å. The U(6)-Se(9) bond length is 2.88 Å. In the seventh U site, U(7) is bonded in a 8-coordinate geometry to one Se(10), one Se(11), one Se(13), one Se(16), one Se(18), one Se(3), one Se(4), and one Se(8) atom. The U(7)-Se(10) bond length is 2.90 Å. The U(7)-Se(11) bond length is 2.93 Å. The U(7)-Se(13) bond length is 3.12 Å. The U(7)-Se(16) bond length is 2.90 Å. The U(7)-Se(18) bond length is 2.91 Å. The U(7)-Se(3) bond length is 2.94 Å. The U(7)-Se(4) bond length is 3.20 Å. The U(7)-Se(8) bond length is 2.91 Å. In the eighth U site, U(8) is bonded in a 8-coordinate geometry to one Se(1), one Se(10), one Se(12), one Se(14), one Se(16), one Se(19), one Se(2), and one Se(5) atom. The U(8)-Se(1) bond length is 3.20 Å. The U(8)-Se(10) bond length is 2.90 Å. The U(8)-Se(12) bond length is 3.12 Å. The U(8)-Se(14) bond length is 2.93 Å. The U(8)-Se(16) bond length is 2.91 Å. The U(8)-Se(19) bond length is 2.91 Å. The U(8)-Se(2) bond length is 2.93 Å. The U(8)-Se(5) bond length is 2.91 Å. In the ninth U site, U(9) is bonded in a 8-coordinate geometry to one Se(1), one Se(13), one Se(14), one Se(15), one Se(20), one Se(3), one Se(6), and one Se(9) atom. The U(9)-Se(1) bond length is 2.94 Å. The U(9)-Se(13) bond length is 2.93 Å. The U(9)-Se(14) bond length is 3.10 Å. The U(9)-Se(15) bond length is 2.91 Å. The U(9)-Se(20) bond length is 2.91 Å. The U(9)-Se(3) bond length is 3.23 Å. The U(9)-Se(6) bond length is 2.90 Å. The U(9)-Se(9) bond length is 2.89 Å. In the tenth U site, U(10) is bonded in a 8-coordinate geometry to one Se(11), one Se(12), one Se(13), one Se(14), one Se(17), one Se(18), one Se(19), and one Se(20) atom. The U(10)-Se(11) bond length is 2.98 Å. The U(10)-Se(12) bond length is 2.95 Å. The U(10)-Se(13) bond length is 2.96 Å. The U(10)-Se(14) bond length is 2.98 Å. The U(10)-Se(17) bond length is 2.89 Å. The U(10)-Se(18) bond length is 2.91 Å. The U(10)-Se(19) bond length is 2.91 Å. The U(10)-Se(20) bond length is 2.90 Å. There are twenty inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted rectangular see-saw-like geometry to one U(1), one U(5), one U(8), and one U(9) atom. In the second Se site, Se(2) is bonded in a distorted rectangular see-saw-like geometry to one U(2), one U(5), one U(6), and one U(8) atom. In the third Se site, Se(3) is bonded in a distorted rectangular see-saw-like geometry to one U(3), one U(5), one U(7), and one U(9) atom. In the fourth Se site, Se(4) is bonded in a distorted rectangular see-saw-like geometry to one U(4), one U(5), one U(6), and one U(7) atom. In the fifth Se site, Se(5) is bonded to one U(1), one U(2), one U(5), and one U(8) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the sixth Se site, Se(6) is bonded to one U(1), one U(3), one U(5), and one U(9) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the seventh Se site, Se(7) is bonded to one U(2), one U(4), one U(5), and one U(6) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the eighth Se site, Se(8) is bonded to one U(3), one U(4), one U(5), and one U(7) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the ninth Se site, Se(9) is bonded to one U(2), one U(3), one U(6), and one U(9) atom to form a mixture of edge and corner-sharing SeU4 tetrahedra. In the tenth Se site, Se(10) is bonded to one U(1), one U(4), one U(7), and one U(8) atom to form a mixture of edge and corner-sharing SeU4 tetrahedra. In the eleventh Se site, Se(11) is bonded to one U(10), one U(3), one U(6), and one U(7) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the twelfth Se site, Se(12) is bonded to one U(10), one U(4), one U(6), and one U(8) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the thirteenth Se site, Se(13) is bonded to one U(1), one U(10), one U(7), and one U(9) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the fourteenth Se site, Se(14) is bonded to one U(10), one U(2), one U(8), and one U(9) atom to form a mixture of edge and corner-sharing SeU4 trigonal pyramids. In the fifteenth Se site, Se(15) is bonded to one U(2), one U(3), one U(6), and one U(9) atom to form a mixture of edge and corner-sharing SeU4 tetrahedra. In the sixteenth Se site, Se(16) is bonded to one U(1), one U(4), one U(7), and one U(8) atom to form a mixture of edge and corner-sharing SeU4 tetrahedra. In the seventeenth Se site, Se(17) is bonded in a distorted rectangular see-saw-like geometry to one U(10), one U(3), one U(4), and one U(6) atom. In the eighteenth Se site, Se(18) is bonded in a distorted rectangular see-saw-like geometry to one U(1), one U(10), one U(3), and one U(7) atom. In the nineteenth Se site, Se(19) is bonded in a distorted rectangular see-saw-like geometry to one U(10), one U(2), one U(4), and one U(8) atom. In the twentieth Se site, Se(20) is bonded in a distorted rectangular see-saw-like geometry to one U(1), one U(10), one U(2), and one U(9) atom.