Ca4Hg9 crystallizes in the cubic P-43m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 11-coordinate geometry to one Hg(1), one Hg(4), one Hg(6), two equivalent Hg(2), two equivalent Hg(5), and four equivalent Hg(3) atoms. In the second Ca site, Ca(2) is bonded in a 10-coordinate geometry to one Hg(6), three equivalent Hg(1), three equivalent Hg(2), and three equivalent Hg(3) atoms. There are six inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a 6-coordinate geometry to three equivalent Ca(1) and three equivalent Ca(2) atoms. In the second Hg site, Hg(2) is bonded in a 7-coordinate geometry to two equivalent Ca(2), four equivalent Ca(1), and one Hg(2) atom. In the third Hg site, Hg(3) is bonded in a 5-coordinate geometry to one Ca(2), four equivalent Ca(1), and one Hg(5) atom. In the fourth Hg site, Hg(4) is bonded in a 3-coordinate geometry to three equivalent Ca(1) and three equivalent Hg(5) atoms. In the fifth Hg site, Hg(5) is bonded in a 8-coordinate geometry to four equivalent Ca(1), two equivalent Hg(3), and two equivalent Hg(4) atoms. In the sixth Hg site, Hg(6) is bonded in a 4-coordinate geometry to one Ca(2) and three equivalent Ca(1) atoms.
Ca4Hg9 crystallizes in the cubic P-43m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 11-coordinate geometry to one Hg(1), one Hg(4), one Hg(6), two equivalent Hg(2), two equivalent Hg(5), and four equivalent Hg(3) atoms. The Ca(1)-Hg(1) bond length is 3.42 Å. The Ca(1)-Hg(4) bond length is 3.29 Å. The Ca(1)-Hg(6) bond length is 3.14 Å. There is one shorter (3.22 Å) and one longer (3.58 Å) Ca(1)-Hg(2) bond length. Both Ca(1)-Hg(5) bond lengths are 3.49 Å. There are two shorter (3.22 Å) and two longer (3.34 Å) Ca(1)-Hg(3) bond lengths. In the second Ca site, Ca(2) is bonded in a 10-coordinate geometry to one Hg(6), three equivalent Hg(1), three equivalent Hg(2), and three equivalent Hg(3) atoms. The Ca(2)-Hg(6) bond length is 3.50 Å. All Ca(2)-Hg(1) bond lengths are 3.29 Å. All Ca(2)-Hg(2) bond lengths are 3.30 Å. All Ca(2)-Hg(3) bond lengths are 3.22 Å. There are six inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a 6-coordinate geometry to three equivalent Ca(1) and three equivalent Ca(2) atoms. In the second Hg site, Hg(2) is bonded in a 7-coordinate geometry to two equivalent Ca(2), four equivalent Ca(1), and one Hg(2) atom. The Hg(2)-Hg(2) bond length is 3.08 Å. In the third Hg site, Hg(3) is bonded in a 5-coordinate geometry to one Ca(2), four equivalent Ca(1), and one Hg(5) atom. The Hg(3)-Hg(5) bond length is 3.09 Å. In the fourth Hg site, Hg(4) is bonded in a 3-coordinate geometry to three equivalent Ca(1) and three equivalent Hg(5) atoms. All Hg(4)-Hg(5) bond lengths are 3.21 Å. In the fifth Hg site, Hg(5) is bonded in a 8-coordinate geometry to four equivalent Ca(1), two equivalent Hg(3), and two equivalent Hg(4) atoms. In the sixth Hg site, Hg(6) is bonded in a 4-coordinate geometry to one Ca(2) and three equivalent Ca(1) atoms.