Mg3TcH7 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to six equivalent H(2) atoms. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one H(1) and three equivalent H(2) atoms. Tc(1) is bonded in an octahedral geometry to six equivalent H(2) atoms. There are two inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to two equivalent Mg(2) atoms. In the second H site, H(2) is bonded in a 3-coordinate geometry to one Mg(1), one Mg(2), and one Tc(1) atom.
Mg3TcH7 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to six equivalent H(2) atoms. All Mg(1)-H(2) bond lengths are 2.12 Å. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one H(1) and three equivalent H(2) atoms. The Mg(2)-H(1) bond length is 1.90 Å. All Mg(2)-H(2) bond lengths are 2.21 Å. Tc(1) is bonded in an octahedral geometry to six equivalent H(2) atoms. All Tc(1)-H(2) bond lengths are 1.74 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to two equivalent Mg(2) atoms. In the second H site, H(2) is bonded in a 3-coordinate geometry to one Mg(1), one Mg(2), and one Tc(1) atom.