Fe10Ni3H42(C2O)54 crystallizes in the trigonal R-3c space group. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(10), one O(2), one O(5), one O(6), and one O(8) atom to form corner-sharing FeO5 square pyramids. The Fe(1)-O(10) bond length is 1.87 Å. The Fe(1)-O(2) bond length is 2.01 Å. The Fe(1)-O(5) bond length is 2.02 Å. The Fe(1)-O(6) bond length is 2.05 Å. The Fe(1)-O(8) bond length is 2.01 Å. In the second Fe site, Fe(2) is bonded in a single-bond geometry to one Ni(1), one O(10), two equivalent O(1), and two equivalent O(7) atoms. The Fe(2)-Ni(1) bond length is 0.10 Å. The Fe(2)-O(10) bond length is 1.91 Å. Both Fe(2)-O(1) bond lengths are 2.08 Å. Both Fe(2)-O(7) bond lengths are 2.05 Å. In the third Fe site, Fe(3) is bonded in an octahedral geometry to six equivalent O(3) atoms. All Fe(3)-O(3) bond lengths are 2.08 Å. Ni(1) is bonded in a single-bond geometry to one Fe(2), one O(9), two equivalent O(1), and two equivalent O(7) atoms. The Ni(1)-O(9) bond length is 2.08 Å. Both Ni(1)-O(1) bond lengths are 2.08 Å. Both Ni(1)-O(7) bond lengths are 2.04 Å. There are eighteen inequivalent C sites. In the first C site, C(1) is bonded in a bent 120 degrees geometry to one C(2), one O(1), and one O(2) atom. The C(1)-C(2) bond length is 1.51 Å. The C(1)-O(1) bond length is 1.25 Å. The C(1)-O(2) bond length is 1.25 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one C(1), one C(3), and one C(7) atom. The C(2)-C(3) bond length is 1.40 Å. The C(2)-C(7) bond length is 1.36 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to one C(2), one C(4), and one H(2) atom. The C(3)-C(4) bond length is 1.39 Å. The C(3)-H(2) bond length is 0.95 Å. In the fourth C site, C(4) is bonded in a trigonal planar geometry to one C(3), one C(5), and one C(8) atom. The C(4)-C(5) bond length is 1.39 Å. The C(4)-C(8) bond length is 1.48 Å. In the fifth C site, C(5) is bonded in a distorted single-bond geometry to one C(4), one C(6), and one H(3) atom. The C(5)-C(6) bond length is 1.39 Å. The C(5)-H(3) bond length is 0.95 Å. In the sixth C site, C(6) is bonded in a trigonal planar geometry to one C(5), one C(7), and one C(9) atom. The C(6)-C(7) bond length is 1.40 Å. The C(6)-C(9) bond length is 1.43 Å. In the seventh C site, C(7) is bonded in a distorted single-bond geometry to one C(2), one C(6), and one H(4) atom. The C(7)-H(4) bond length is 0.95 Å. In the eighth C site, C(8) is bonded in a distorted bent 120 degrees geometry to one C(4), one O(3), and one O(4) atom. The C(8)-O(3) bond length is 1.20 Å. The C(8)-O(4) bond length is 1.27 Å. In the ninth C site, C(9) is bonded in a linear geometry to one C(10) and one C(6) atom. The C(9)-C(10) bond length is 1.18 Å. In the tenth C site, C(10) is bonded in a linear geometry to one C(11) and one C(9) atom. The C(10)-C(11) bond length is 1.45 Å. In the eleventh C site, C(11) is bonded in a trigonal planar geometry to one C(10), one C(12), and one C(16) atom. The C(11)-C(12) bond length is 1.39 Å. The C(11)-C(16) bond length is 1.39 Å. In the twelfth C site, C(12) is bonded in a distorted single-bond geometry to one C(11), one C(13), and one H(5) atom. The C(12)-C(13) bond length is 1.38 Å. The C(12)-H(5) bond length is 0.95 Å. In the thirteenth C site, C(13) is bonded in a trigonal planar geometry to one C(12), one C(14), and one C(17) atom. The C(13)-C(14) bond length is 1.38 Å. The C(13)-C(17) bond length is 1.50 Å. In the fourteenth C site, C(14) is bonded in a distorted single-bond geometry to one C(13), one C(15), and one H(6) atom. The C(14)-C(15) bond length is 1.39 Å. The C(14)-H(6) bond length is 0.95 Å. In the fifteenth C site, C(15) is bonded in a trigonal planar geometry to one C(14), one C(16), and one C(18) atom. The C(15)-C(16) bond length is 1.38 Å. The C(15)-C(18) bond length is 1.50 Å. In the sixteenth C site, C(16) is bonded in a distorted single-bond geometry to one C(11), one C(15), and one H(7) atom. The C(16)-H(7) bond length is 0.95 Å. In the seventeenth C site, C(17) is bonded in a distorted bent 120 degrees geometry to one C(13), one O(5), and one O(6) atom. The C(17)-O(5) bond length is 1.25 Å. The C(17)-O(6) bond length is 1.26 Å. In the eighteenth C site, C(18) is bonded in a distorted bent 120 degrees geometry to one C(15), one O(7), and one O(8) atom. The C(18)-O(7) bond length is 1.25 Å. The C(18)-O(8) bond length is 1.25 Å. There are seven inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one O(4) atom. The H(1)-O(4) bond length is 0.84 Å. In the second H site, H(2) is bonded in a single-bond geometry to one C(3) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(5) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(7) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(12) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one C(14) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one C(16) atom. There are ten inequivalent O sites. In the first O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one C(17) atom. In the second O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one C(17) atom. In the third O site, O(9) is bonded in a single-bond geometry to one Ni(1) atom. In the fourth O site, O(10) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent Fe(1) atoms. In the fifth O site, O(7) is bonded in a 3-coordinate geometry to one Fe(2), one Ni(1), and one C(18) atom. In the sixth O site, O(1) is bonded in a distorted single-bond geometry to one Fe(2), one Ni(1), and one C(1) atom. In the seventh O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one C(1) atom. In the eighth O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(3) and one C(8) atom. In the ninth O site, O(4) is bonded in a water-like geometry to one C(8) and one H(1) atom. In the tenth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one C(18) atom. Linkers: 36 [O]C(=O)c1cc(C#Cc2cc(C([O])=O)cc(C(=O)O)c2)cc(C([O])=O)c1. Metal clusters: 18 [Fe].[O][Ni]123O[C]O[Fe]45(O[C]O[Fe](O[C]O4)(O[C]O1)(O[C]O2)O5)O[C]O3 ,6 O[C]O[Fe](O[C]O)(O[C]O)(O[C]O)(O[C]O)O[C]O. RCSR code: soc. The MOF has largest included sphere 10.34 A, density 0.97 g/cm3, surface area 3548.05 m2/g, accessible volume 0.57 cm3/g