LiMgB3(NH9)2 crystallizes in the hexagonal P6_3 space group. Li(1) is bonded to three equivalent H(1) and three equivalent H(4) atoms to form LiH6 octahedra that share corners with six equivalent B(1)H4 tetrahedra. Mg(1) is bonded to one N(1), one N(2), three equivalent H(5), and three equivalent H(6) atoms to form MgH6N2 hexagonal bipyramids that share edges with three equivalent B(1)H4 tetrahedra. B(1) is bonded to one H(1), one H(4), one H(5), and one H(6) atom to form BH4 tetrahedra that share corners with two equivalent Li(1)H6 octahedra and  an edgeedge with one Mg(1)H6N2 hexagonal bipyramid. The corner-sharing octahedral tilt angles range from 45-54°. There are two inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1) and three equivalent H(2,3) atoms. In the second N site, N(2) is bonded in a distorted tetrahedral geometry to one Mg(1) and three equivalent H(2,3) atoms. There are five inequivalent H sites. In the first H site, H(1) is bonded in a bent 120 degrees geometry to one Li(1) and one B(1) atom. In the second H site, H(2,3) is bonded in a single-bond geometry to one N(1) atom. In the third H site, H(4) is bonded in a distorted bent 150 degrees geometry to one Li(1) and one B(1) atom. In the fourth H site, H(5) is bonded in a distorted L-shaped geometry to one Mg(1) and one B(1) atom. In the fifth H site, H(6) is bonded in a distorted L-shaped geometry to one Mg(1) and one B(1) atom.
LiMgB3(NH9)2 crystallizes in the hexagonal P6_3 space group. Li(1) is bonded to three equivalent H(1) and three equivalent H(4) atoms to form LiH6 octahedra that share corners with six equivalent B(1)H4 tetrahedra. All Li(1)-H(1) bond lengths are 1.97 Å. All Li(1)-H(4) bond lengths are 2.01 Å. Mg(1) is bonded to one N(1), one N(2), three equivalent H(5), and three equivalent H(6) atoms to form MgH6N2 hexagonal bipyramids that share edges with three equivalent B(1)H4 tetrahedra. The Mg(1)-N(1) bond length is 2.13 Å. The Mg(1)-N(2) bond length is 2.12 Å. All Mg(1)-H(5) bond lengths are 2.10 Å. All Mg(1)-H(6) bond lengths are 2.13 Å. B(1) is bonded to one H(1), one H(4), one H(5), and one H(6) atom to form BH4 tetrahedra that share corners with two equivalent Li(1)H6 octahedra and  an edgeedge with one Mg(1)H6N2 hexagonal bipyramid. The corner-sharing octahedral tilt angles range from 45-54°. The B(1)-H(1) bond length is 1.22 Å. The B(1)-H(4) bond length is 1.22 Å. The B(1)-H(5) bond length is 1.24 Å. The B(1)-H(6) bond length is 1.23 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1) and three equivalent H(2,3) atoms. All N(1)-H(2,3) bond lengths are 1.03 Å. In the second N site, N(2) is bonded in a distorted tetrahedral geometry to one Mg(1) and three equivalent H(2,3) atoms. All N(2)-H(2,3) bond lengths are 1.03 Å. There are five inequivalent H sites. In the first H site, H(1) is bonded in a bent 120 degrees geometry to one Li(1) and one B(1) atom. In the second H site, H(2,3) is bonded in a single-bond geometry to one N(1) atom. In the third H site, H(4) is bonded in a distorted bent 150 degrees geometry to one Li(1) and one B(1) atom. In the fourth H site, H(5) is bonded in a distorted L-shaped geometry to one Mg(1) and one B(1) atom. In the fifth H site, H(6) is bonded in a distorted L-shaped geometry to one Mg(1) and one B(1) atom.