EuH3(CO)6 crystallizes in the triclinic P1 space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(9) atom. The Eu(1)-O(1) bond length is 2.75 Å. The Eu(1)-O(2) bond length is 2.51 Å. The Eu(1)-O(3) bond length is 2.77 Å. The Eu(1)-O(4) bond length is 2.49 Å. The Eu(1)-O(5) bond length is 2.47 Å. The Eu(1)-O(6) bond length is 2.53 Å. The Eu(1)-O(7) bond length is 2.38 Å. The Eu(1)-O(9) bond length is 2.38 Å. In the second Eu site, Eu(2) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(3), one O(7), one O(8), and one O(9) atom. The Eu(2)-O(1) bond length is 2.38 Å. The Eu(2)-O(10) bond length is 2.49 Å. The Eu(2)-O(11) bond length is 2.47 Å. The Eu(2)-O(12) bond length is 2.53 Å. The Eu(2)-O(3) bond length is 2.38 Å. The Eu(2)-O(7) bond length is 2.75 Å. The Eu(2)-O(8) bond length is 2.51 Å. The Eu(2)-O(9) bond length is 2.77 Å. There are eight inequivalent C sites. In the first C site, C(1,7) is bonded in a bent 120 degrees geometry to one C(2,8); one O(1); and one O(2) atom. The C(1,7)-C(2,8) bond length is 1.48 Å. The C(1,7)-O(1) bond length is 1.26 Å. The C(1,7)-O(2) bond length is 1.26 Å. In the second C site, C(2,8) is bonded in a distorted trigonal planar geometry to one C(1,7); one C(3,9); and one H(1,4) atom. The C(2,8)-C(3,9) bond length is 1.33 Å. The C(2,8)-H(1,4) bond length is 1.14 Å. In the third C site, C(3,9) is bonded in a distorted trigonal planar geometry to one C(2,8); one C(4,10); and one H(2,5) atom. The C(3,9)-C(4,10) bond length is 1.49 Å. The C(3,9)-H(2,5) bond length is 1.14 Å. In the fourth C site, C(4,10) is bonded in a bent 120 degrees geometry to one C(3,9); one O(3); and one O(4) atom. The C(4,10)-O(3) bond length is 1.27 Å. The C(4,10)-O(4) bond length is 1.25 Å. In the fifth C site, C(5) is bonded in a bent 120 degrees geometry to one C(6), one O(5), and one O(6) atom. The C(5)-C(6) bond length is 1.51 Å. The C(5)-O(5) bond length is 1.25 Å. The C(5)-O(6) bond length is 1.27 Å. In the sixth C site, C(6) is bonded in a distorted trigonal planar geometry to one C(12), one C(5), and one H(3) atom. The C(6)-C(12) bond length is 1.31 Å. The C(6)-H(3) bond length is 1.14 Å. In the seventh C site, C(11) is bonded in a bent 120 degrees geometry to one C(12), one O(11), and one O(12) atom. The C(11)-C(12) bond length is 1.51 Å. The C(11)-O(11) bond length is 1.25 Å. The C(11)-O(12) bond length is 1.27 Å. In the eighth C site, C(12) is bonded in a distorted trigonal planar geometry to one C(11), one C(6), and one H(6) atom. The C(12)-H(6) bond length is 1.14 Å. There are four inequivalent H sites. In the first H site, H(1,4) is bonded in a single-bond geometry to one C(2,8) atom. In the second H site, H(2,5) is bonded in a single-bond geometry to one C(3,9) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(6) atom. In the fourth H site, H(6) is bonded in a single-bond geometry to one C(12) atom. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 1-coordinate geometry to one Eu(1); one Eu(2); and one C(1,7) atom. In the second O site, O(2) is bonded in a distorted water-like geometry to one Eu(1) and one C(1,7) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to one Eu(1); one Eu(2); and one C(4,10) atom. In the fourth O site, O(4) is bonded in a distorted water-like geometry to one Eu(1) and one C(4,10) atom. In the fifth O site, O(5) is bonded in a distorted L-shaped geometry to one Eu(1) and one C(5) atom. In the sixth O site, O(6) is bonded in a distorted L-shaped geometry to one Eu(1) and one C(5) atom. In the seventh O site, O(7) is bonded in a 1-coordinate geometry to one Eu(1); one Eu(2); and one C(1,7) atom. The O(7)-C(1,7) bond length is 1.26 Å. In the eighth O site, O(8) is bonded in a distorted water-like geometry to one Eu(2) and one C(1,7) atom. The O(8)-C(1,7) bond length is 1.26 Å. In the ninth O site, O(9) is bonded in a 1-coordinate geometry to one Eu(1); one Eu(2); and one C(4,10) atom. The O(9)-C(4,10) bond length is 1.27 Å. In the tenth O site, O(10) is bonded in a distorted water-like geometry to one Eu(2) and one C(4,10) atom. The O(10)-C(4,10) bond length is 1.25 Å. In the eleventh O site, O(11) is bonded in a distorted L-shaped geometry to one Eu(2) and one C(11) atom. In the twelfth O site, O(12) is bonded in a distorted L-shaped geometry to one Eu(2) and one C(11) atom. Linkers: 3 [O]C(=O)/C=C/C([O])=O. Metal clusters: 2 [Eu]. RCSR code: tcs. The MOF has largest included sphere 5.81 A, density 1.51 g/cm3, surface area 2796.31 m2/g, accessible volume 0.42 cm3/g