TmBH4 crystallizes in the monoclinic C2 space group. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 12-coordinate geometry to two equivalent H(1), two equivalent H(2), two equivalent H(3), two equivalent H(5), and four equivalent H(4) atoms. In the second Tm site, Tm(2) is bonded to one H(4), two equivalent H(1), two equivalent H(2), two equivalent H(3), two equivalent H(5), and three equivalent H(6) atoms to form TmH12 cuboctahedra that share edges with seven equivalent Tm(2)H12 cuboctahedra, edges with two equivalent B(1)H4 tetrahedra, and edges with four equivalent B(2)H4 tetrahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded to two equivalent H(1) and two equivalent H(2) atoms to form BH4 tetrahedra that share edges with four equivalent Tm(2)H12 cuboctahedra. In the second B site, B(2) is bonded to one H(3), one H(4), one H(5), and one H(6) atom to form BH4 tetrahedra that share edges with four equivalent Tm(2)H12 cuboctahedra. There are six inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one Tm(1), two equivalent Tm(2), and one B(1) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one Tm(1), two equivalent Tm(2), and one B(1) atom. In the third H site, H(3) is bonded in a distorted single-bond geometry to one Tm(1), two equivalent Tm(2), and one B(2) atom. In the fourth H site, H(4) is bonded in a distorted single-bond geometry to one Tm(2), two equivalent Tm(1), and one B(2) atom. In the fifth H site, H(5) is bonded in a distorted single-bond geometry to one Tm(1), two equivalent Tm(2), and one B(2) atom. In the sixth H site, H(6) is bonded in a distorted single-bond geometry to three equivalent Tm(2) and one B(2) atom.
TmBH4 crystallizes in the monoclinic C2 space group. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 12-coordinate geometry to two equivalent H(1), two equivalent H(2), two equivalent H(3), two equivalent H(5), and four equivalent H(4) atoms. Both Tm(1)-H(1) bond lengths are 2.24 Å. Both Tm(1)-H(2) bond lengths are 2.35 Å. Both Tm(1)-H(3) bond lengths are 2.27 Å. Both Tm(1)-H(5) bond lengths are 2.31 Å. There are two shorter (2.29 Å) and two longer (2.35 Å) Tm(1)-H(4) bond lengths. In the second Tm site, Tm(2) is bonded to one H(4), two equivalent H(1), two equivalent H(2), two equivalent H(3), two equivalent H(5), and three equivalent H(6) atoms to form TmH12 cuboctahedra that share edges with seven equivalent Tm(2)H12 cuboctahedra, edges with two equivalent B(1)H4 tetrahedra, and edges with four equivalent B(2)H4 tetrahedra. The Tm(2)-H(4) bond length is 2.23 Å. There is one shorter (2.22 Å) and one longer (2.36 Å) Tm(2)-H(1) bond length. There is one shorter (2.23 Å) and one longer (2.34 Å) Tm(2)-H(2) bond length. There is one shorter (2.36 Å) and one longer (2.41 Å) Tm(2)-H(3) bond length. There is one shorter (2.28 Å) and one longer (2.34 Å) Tm(2)-H(5) bond length. There are a spread of Tm(2)-H(6) bond distances ranging from 2.27-2.40 Å. There are two inequivalent B sites. In the first B site, B(1) is bonded to two equivalent H(1) and two equivalent H(2) atoms to form BH4 tetrahedra that share edges with four equivalent Tm(2)H12 cuboctahedra. Both B(1)-H(1) bond lengths are 1.31 Å. Both B(1)-H(2) bond lengths are 1.29 Å. In the second B site, B(2) is bonded to one H(3), one H(4), one H(5), and one H(6) atom to form BH4 tetrahedra that share edges with four equivalent Tm(2)H12 cuboctahedra. The B(2)-H(3) bond length is 1.26 Å. The B(2)-H(4) bond length is 1.28 Å. The B(2)-H(5) bond length is 1.27 Å. The B(2)-H(6) bond length is 1.27 Å. There are six inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one Tm(1), two equivalent Tm(2), and one B(1) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one Tm(1), two equivalent Tm(2), and one B(1) atom. In the third H site, H(3) is bonded in a distorted single-bond geometry to one Tm(1), two equivalent Tm(2), and one B(2) atom. In the fourth H site, H(4) is bonded in a distorted single-bond geometry to one Tm(2), two equivalent Tm(1), and one B(2) atom. In the fifth H site, H(5) is bonded in a distorted single-bond geometry to one Tm(1), two equivalent Tm(2), and one B(2) atom. In the sixth H site, H(6) is bonded in a distorted single-bond geometry to three equivalent Tm(2) and one B(2) atom.