RbCaMg6 crystallizes in the orthorhombic Amm2 space group. Rb(1) is bonded to two equivalent Ca(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(3) atoms to form RbCa2Mg10 cuboctahedra that share corners with six equivalent Rb(1)Ca2Mg10 cuboctahedra, edges with four equivalent Ca(1)Rb2Mg10 cuboctahedra, faces with two equivalent Rb(1)Ca2Mg10 cuboctahedra, and faces with two equivalent Ca(1)Rb2Mg10 cuboctahedra. Ca(1) is bonded to two equivalent Rb(1), two equivalent Mg(2), four equivalent Mg(1), and four equivalent Mg(3) atoms to form CaRb2Mg10 cuboctahedra that share corners with six equivalent Ca(1)Rb2Mg10 cuboctahedra, edges with four equivalent Rb(1)Ca2Mg10 cuboctahedra, faces with two equivalent Rb(1)Ca2Mg10 cuboctahedra, and faces with two equivalent Ca(1)Rb2Mg10 cuboctahedra. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 11-coordinate geometry to two equivalent Rb(1), two equivalent Ca(1), one Mg(1), two equivalent Mg(2), two equivalent Mg(3), and two equivalent Mg(4) atoms. In the second Mg site, Mg(2) is bonded in a 2-coordinate geometry to two equivalent Ca(1) and four equivalent Mg(1) atoms. In the third Mg site, Mg(3) is bonded in a 4-coordinate geometry to two equivalent Rb(1), two equivalent Ca(1), and two equivalent Mg(1) atoms. In the fourth Mg site, Mg(4) is bonded in a 2-coordinate geometry to two equivalent Rb(1) and four equivalent Mg(1) atoms.
RbCaMg6 crystallizes in the orthorhombic Amm2 space group. Rb(1) is bonded to two equivalent Ca(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(3) atoms to form RbCa2Mg10 cuboctahedra that share corners with six equivalent Rb(1)Ca2Mg10 cuboctahedra, edges with four equivalent Ca(1)Rb2Mg10 cuboctahedra, faces with two equivalent Rb(1)Ca2Mg10 cuboctahedra, and faces with two equivalent Ca(1)Rb2Mg10 cuboctahedra. Both Rb(1)-Ca(1) bond lengths are 3.56 Å. Both Rb(1)-Mg(4) bond lengths are 3.49 Å. All Rb(1)-Mg(1) bond lengths are 3.48 Å. There are two shorter (3.44 Å) and two longer (3.59 Å) Rb(1)-Mg(3) bond lengths. Ca(1) is bonded to two equivalent Rb(1), two equivalent Mg(2), four equivalent Mg(1), and four equivalent Mg(3) atoms to form CaRb2Mg10 cuboctahedra that share corners with six equivalent Ca(1)Rb2Mg10 cuboctahedra, edges with four equivalent Rb(1)Ca2Mg10 cuboctahedra, faces with two equivalent Rb(1)Ca2Mg10 cuboctahedra, and faces with two equivalent Ca(1)Rb2Mg10 cuboctahedra. Both Ca(1)-Mg(2) bond lengths are 3.50 Å. There are two shorter (3.33 Å) and two longer (3.70 Å) Ca(1)-Mg(1) bond lengths. All Ca(1)-Mg(3) bond lengths are 3.41 Å. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 11-coordinate geometry to two equivalent Rb(1), two equivalent Ca(1), one Mg(1), two equivalent Mg(2), two equivalent Mg(3), and two equivalent Mg(4) atoms. The Mg(1)-Mg(1) bond length is 3.27 Å. There is one shorter (3.49 Å) and one longer (3.54 Å) Mg(1)-Mg(2) bond length. Both Mg(1)-Mg(3) bond lengths are 3.42 Å. Both Mg(1)-Mg(4) bond lengths are 3.38 Å. In the second Mg site, Mg(2) is bonded in a 2-coordinate geometry to two equivalent Ca(1) and four equivalent Mg(1) atoms. In the third Mg site, Mg(3) is bonded in a 4-coordinate geometry to two equivalent Rb(1), two equivalent Ca(1), and two equivalent Mg(1) atoms. In the fourth Mg site, Mg(4) is bonded in a 2-coordinate geometry to two equivalent Rb(1) and four equivalent Mg(1) atoms.