Increasing Complexity in the Uranyl IonâKemp's Triacid System: From

Article pubs.acs.org/crystal

Increasing Complexity in the Uranyl Ion−Kemp’s Triacid System: From One- and Two-Dimensional Polymers to Uranyl−Copper(II) Dodeca- and Hexadecanuclear Species Pierre Thuéry* CEA, IRAMIS, NIMBE, LCMCE, UMR 3299 CEA/CNRS, Bât. 125, 91191 Gif-sur-Yvette, France S Supporting Information *

ABSTRACT: Kemp’s triacid (cis,cis-1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid, LH3) has recently been shown to be a versatile ligand for the uranyl ion, with the presence of additional nickel(II) cations allowing isolation of nanotubular and cage species in particular. The high sensitivity of the uranyl−LH3 system to variations in the experimental conditions was the incentive for the present investigation of different solvents as organic components in solvo-hydrothermal synthesis methods and of different additional species (metal cations, 2,2′-bipyridine). Reaction of LH3 with uranyl ions under purely hydrothermal conditions gives [UO2(LH2)2(H2O)2]·2H2O (1), an unremarkable mononuclear complex. In the presence of manganese nitrate and in water−THF or water−methanol, respectively, the complexes [Hbipy][UO2(L)]·0.5H2O·0.25THF (2) and [(UO2)3(MeL)2(OH)2(H2O)]·8MeOH (3) were obtained; 2 is a two-dimensional (2D) species, while 3 is one-dimensional (1D) and contains the monoester derivative of LH3, formed in situ. Another 2D compound, [UO2Tb{(L)2H}(H2O)2] (4), crystallizes in the presence of terbium(III) nitrate. The three complexes [(UO2)8{(L)6H2}(H2O)6]·H2O (5), [(UO2)8{(L)6H2}(H2O)6]·3H2O (6), and [Cu2(C2O4)(bipy)2(THF)2][(UO2)8{(L)6H}(H2O)6]2·4H2O·7THF (7), which were obtained in the presence of copper(II) or nickel(II) cations, all contain homometallic octanuclear cage-like species analogous to that previously reported. The most interesting complexes in this series, [(UO2)8Cu4(L)8(H2O)16]·9H2O (8) and [(UO2)10Cu6(L)10(OH)2(H2O)7] (9), were obtained together in water−THF and in the presence of copper(II) cations. Compound 8 is a dodecanuclear metallacycle comprising four (UO2)2Cu trinuclear subunits, in which the central copper atom is bound to two uranyl oxo groups, arranged in helical geometry. Compound 9 is a large, hexadecanuclear cage-like species devoid of any crystallographic symmetry. In both 8 and 9, uranyl ions are topologically sufficient for the formation of the cyclic or cage molecules, and the hydrated copper ions are located inside. The curved shape of the three-pronged Kemp’s tricarboxylate ligand appears well suited to the formation of closed species (nanotubes, rings, and cages), which are in all cases coated on the outside by the hydrophobic parts of the ligands.

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INTRODUCTION Among the many carboxylates that have been used in the design of uranyl−organic coordination polymers and frameworks (UOFs),1 some (but by no means all) give complexes whose structures are extremely sensitive to the experimental conditions used and are easily varied in terms of connectivity and dimensionality through addition of secondary cations or templating species. This is particularly to be expected from polycarboxylates, with each coordinating site able to assume different bonding modes, thus resulting in various metal−ligand associations, possibly close in energy and most often largely unpredictable. The structural effects of additional d-block metal cations and of neutral or protonated nitrogen-containing molecules on the uranyl complexes formed by common polycarboxylates have been investigated recently,2 as well as the effect of the organic solvent in the case of solvo-hydrothermal synthetic methods.3 In the course of this work, Kemp’s triacid (cis,cis-1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid, LH3)4 was shown to be a quite extraordinary ligand for uranyl ions, giving either one-dimensional (1D) polymeric, nanotubular, or octanuclear cage-like species.5 The two latter © 2014 American Chemical Society

architectures are formed in the presence of additional nickel(II) cations, either alone (heterometallic uranyl−nickel nanotubules) or associated with 2,2′-bipyridine (bipy) and thus separated from the homometallic octanuclear cages as counterions. This ligand, which has seldom been used in coordination chemistry,6 had been chosen in the hope that its rigid, three-pronged geometry would favor the formation of closed or cyclic species with the uranyl ion, as was indeed observed. The synthesis of complexes with such geometries is somewhat tricky due to the well-known tendency of the linear uranyl ion to organize its ligands in its equatorial plane, which most often results in the formation of quasi-planar one- or two-dimensional (2D) assemblies. Cyclic or cage-like polynuclear complexes can however be synthesized from suitably curved polytopic ligands.7 Worthy of note in this respect are also the remarkable nanospheres found in the uranyl peroxide system8 and the large capsules built from calixarene carboxylates.9 Nanotubular uranyl-containing species are barely Received: March 12, 2014 Revised: April 11, 2014 Published: April 14, 2014 2665

dx.doi.org/10.1021/cg500353k | Cryst. Growth Des. 2014, 14, 2665−2676

Crystal Growth & Design

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autogenous pressure, giving light green crystals of complex 7 in low yield overnight. [(UO2)8Cu4(L)8(H2O)16]·9H2O (8) and [(UO2)10Cu6(L)10(OH)2(H2O)7] (9). Kemp’s triacid (13 mg, 0.05 mmol), UO2(NO3)2·6H2O (25 mg, 0.05 mmol), Cu(NO3)2·2.5H2O (12 mg, 0.05 mmol), demineralized water (0.8 mL), and THF (0.4 mL) were placed in a 15 mL tightly closed glass vessel and heated at 140 °C under autogenous pressure, giving a mixture of light green crystals of complexes 8 and 9 in low yield overnight. In some experiments, yellow crystals were obtained alongside, which could not be characterized since they deteriorated extremely rapidly when removed from the solution. Crystallography. The data were collected at 150(2) K on a Nonius Kappa-CCD area detector diffractometer13 using graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). The crystals were introduced into glass capillaries with a protecting coating of Paratone-N oil (Hampton Research). The unit cell parameters were determined from 10 frames, then refined on all data. The data (combinations of φ- and ωscans with a minimum redundancy of 4 for 90% of the reflections) were processed with HKL2000.14 Absorption effects were corrected empirically with the program SCALEPACK.14 The structures were solved by direct methods, expanded by subsequent Fourier-difference synthesis, and refined by full-matrix least-squares on F2 with SHELXL97.15 All non-hydrogen atoms were refined with anisotropic displacement parameters. The hydrogen atoms bound to oxygen and nitrogen atoms were found on Fourier-difference maps, except when indicated below. The carbon-bound hydrogen atoms were introduced at calculated positions in all compounds. All hydrogen atoms were treated as riding atoms with an isotropic displacement parameter equal to 1.2 times that of the parent atom (1.5 for CH3). Special details for each compound are as follows. Complex 1. The solvent water molecule is disordered over two sites close to one another, which have been refined with occupancy parameters constrained to sum to unity. Restraints on displacement parameters were applied for four exceedingly anisotropic atoms (O6, O7, C11, and C12). The hydrogen atoms of the disordered water molecule were not found. Complex 2. The badly resolved THF solvent molecule was given an occupancy factor of 0.25 in order to retain acceptable displacement parameters, and it was refined with restraints on bond lengths, angles, and displacement parameters. Complex 3. The hydroxide ion containing O11 is disordered over two positions which have been refined with occupancy parameters constrained to sum to unity and restraints on displacement parameters; the associated hydrogen atoms were not found. No improvement of the refinement was obtained upon considering possible twinning. Large voids in the lattice indicate the presence of unresolved solvent molecules, which were taken into account with the PLATON/ SQUEEZE software.16 The potential solvent accessible void volume corresponds to 178 Å3 per asymmetric unit. In the crystal structure of pure methanol,17 four molecules occupy a volume of about 200 Å3, not too far from the present free space. The SQUEEZE program added the contribution of 73 electrons per asymmetric unit. This value matches nicely the number of electrons corresponding to four methanol molecules, which were thus added to the formula. However, the possibility of water molecules being present instead of one or several of these methanol molecules cannot be ruled out. Complex 4. The hydrogen atom bound to the carboxylate atom O7 was given an occupancy factor of 0.5 for charge equilibrium and to account for its closeness to its image by a 2-fold rotation axis. Atom O7 and its symmetry equivalent are thus hydrogen bonded to one another through a hydrogen atom disordered over the two possible sites. Complex 5. Restraints on displacement parameters were applied for some atoms which became exceedingly anisotropic, possibly as a result of unresolved disorder. Neither the hydrogen atoms of the water molecules, nor that necessarily retained by one carboxylic function for charge equilibrium, which is probably disordered, have been found. Some voids in the lattice indicate the presence of other, unresolved water solvent molecules. The largest residual electron density peak is however located at 0.71 Å from U1 and is possibly a result of imperfect absorption corrections.

more common, but examples have been found in very diverse families such as phosphates and phosphonates,10 selenates,11 and carboxylates.12 In the case of Kemp’s triacid, the notable effects of the organic solvent component (acetonitrile or N-methyl-2pyrrolidone, NMP) in solvo-hydrothermal synthesis methods, and the easy selection between two remarkable topologies through the use of additional species, suggest that this ligand is a good candidate for an investigation of variations in the synthesis conditions, with the possible outcome of original architectures. The crystal structures of nine complexes obtained from experiments in which different additional metal ions (MnII, NiII, CuII or TbIII) were added, with or without bipy, and the solvent was either pure water or mixtures of water and tetrahydrofuran (THF), methanol or ethanol, are reported herein. As expected, these structures display a remarkable progression from very simple to quite complex.

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EXPERIMENTAL SECTION

Synthesis. Uranium is a radioactive and chemically toxic element, and uranium-containing samples must be handled with suitable care and protection. UO2(NO3)2·6H2O (depleted uranium, R. P. Normapur, 99%) and Ni(NO3)2·6H2O were purchased from Prolabo, Mn(NO3)2·4H2O was from Merck, and Cu(NO3)2·2.5H2O, Tb(NO3)3·5H2O, and Kemp’s triacid were from Aldrich. All were used without further purification. [UO2(LH2)2(H2O)2]·2H2O (1). Kemp’s triacid (13 mg, 0.05 mmol), UO2(NO3)2·6H2O (25 mg, 0.05 mmol), Ni(NO3)2·6H2O (16 mg, 0.06 mmol), and demineralized water (1.2 mL) were placed in a 15 mL tightly closed glass vessel and heated at 140 °C under autogenous pressure, giving light yellow crystals of complex 1 in low yield within 2 weeks. [Hbipy][UO2(L)]·0.5H2O·0.25THF (2). Kemp’s triacid (13 mg, 0.05 mmol), UO2(NO3)2·6H2O (25 mg, 0.05 mmol), Mn(NO3)2·4H2O (13 mg, 0.05 mmol), 2,2′-bipyridine (8 mg, 0.05 mmol), demineralized water (0.9 mL), and THF (0.4 mL) were placed in a 15 mL tightly closed glass vessel and heated at 140 °C under autogenous pressure, giving light yellow crystals of complex 2 in low yield within 2 weeks. [(UO2)3(MeL)2(OH)2(H2O)]·8MeOH (3). Kemp’s triacid (13 mg, 0.05 mmol), UO2(NO3)2·6H2O (25 mg, 0.05 mmol), Mn(NO3)2·4H2O (13 mg, 0.05 mmol), demineralized water (0.9 mL), and methanol (0.4 mL) were placed in a 15 mL tightly closed glass vessel and heated at 140 °C under autogenous pressure, giving light yellow crystals of complex 3 in low yield, mixed with an amorphous white powder which was not further characterized, within one month. [UO2Tb{(L)2H}(H2O)2] (4). Kemp’s triacid (13 mg, 0.05 mmol), UO2(NO3)2·6H2O (25 mg, 0.05 mmol), Tb(NO3)3·5H2O (22 mg, 0.05 mmol), demineralized water (0.8 mL), and THF (0.4 mL) were placed in a 15 mL tightly closed glass vessel and heated at 140 °C under autogenous pressure, giving light yellow crystals of complex 4 in low yield within 3 weeks. [(UO2)8{(L)6H2}(H2O)6]·H2O (5). Kemp’s triacid (13 mg, 0.05 mmol), UO2(NO3)2·6H2O (25 mg, 0.05 mmol), Cu(NO3)2·2.5H2O (12 mg, 0.05 mmol), demineralized water (0.8 mL), and ethanol (0.5 mL) were placed in a 15 mL tightly closed glass vessel and heated at 140 °C under autogenous pressure, giving light yellow crystals of complex 5 in low yield within 2 weeks. [(UO2)8{(L)6H2}(H2O)6]·3H2O (6). Kemp’s triacid (13 mg, 0.05 mmol), UO2(NO3)2·6H2O (25 mg, 0.05 mmol), Ni(NO3)2·6H2O (16 mg, 0.06 mmol), demineralized water (0.9 mL), and THF (0.4 mL) were placed in a 15 mL tightly closed glass vessel and heated at 140 °C under autogenous pressure, giving light yellow crystals of complex 6 in low yield within 2 weeks, mixed with crystals of compound 5. [Cu2(C2O4)(bipy)2(THF)2][(UO2)8{(L)6H}(H2O)6]2·4H2O·7THF (7). Kemp’s triacid (13 mg, 0.05 mmol), UO2(NO3)2·6H2O (25 mg, 0.05 mmol), Cu(NO3)2·2.5H2O (12 mg, 0.05 mmol), 2,2′-bipyridine (8 mg, 0.05 mmol), demineralized water (0.6 mL), and THF (0.5 mL) were placed in a 15 mL tightly closed glass vessel and heated at 140 °C under 2666


chemical formula M (g mol−1) cryst syst space group a (Å) b (Å) c (Å) α (deg) β (deg) γ (deg) V (Å3) Z Dcalcd (g cm−3) μ (Mo Kα) (mm−1) F(000) reflns collcd indep reflns obsd reflns [I > 2σ(I)] Rint params refined R1 wR2 S Δρmin (e Å−3) Δρmax (e Å−3)

2 C23H27N2O8.75U 709.50 orthorhombic Pbcn 20.6245(7) 16.1559(3) 16.2561(6) 90 90 90 5416.7(3) 8 1.740 6.041 2728 134571 8257 6277 0.023 351 0.032 0.087 0.995 −1.49 1.33

1

C24H42O18U 856.61 monoclinic P21/c 8.1312(2) 25.5646(11) 8.1350(4) 90 117.704(2) 90 1497.17(11) 2 1.900 5.502 844 38995 4459 3506 0.023 209 0.032 0.079 1.115 −1.50 2.15

3 C34H72O29U3 1659.01 monoclinic C2/m 12.3287(11) 23.6161(13) 16.4473(15) 90 105.034(4) 90 4624.8(6) 4 2.383 10.576 3136 69550 4498 3480 0.086 246 0.072 0.219 1.055 −3.47 4.56

Table 1. Crystal Data and Structure Refinement Details C24H35O16TbU 976.47 monoclinic C2/c 25.5369(15) 7.9206(5) 16.8430(6) 90 113.677(3) 90 3120.0(3) 4 2.079 7.502 1856 95484 4755 4251 0.039 195 0.029 0.078 1.021 −1.08 2.25

4 C72H106O59U8 3819.81 monoclinic C2/c 25.4173(9) 15.8195(3) 28.8395(10) 90 110.2414(17) 90 10879.9(6) 4 2.332 11.956 6984 196965 16609 11596 0.052 637 0.046 0.113 1.040 −2.43 4.29

5 C72H110O61U8 3855.84 monoclinic P21/n 19.2648(4) 14.8909(2) 20.4180(4) 90 94.5172(11) 90 5839.12(18) 2 2.193 11.141 3532 217252 17798 15104 0.042 664 0.033 0.092 1.135 −1.50 1.91

6 C202H302Cu2N4O133U16 8850.04 triclinic P1̅ 16.5835(5) 20.1557(7) 21.1177(4) 88.6196(18) 87.0438(18) 79.7935(15) 6936.9(3) 1 2.119 9.544 4136 422030 35796 26727 0.058 1696 0.038 0.091 1.014 −1.81 2.17

7 C96H170Cu4O89U8 4906.72 tetragonal I4 24.2270(9) 24.2270(9) 15.9191(4) 90 90 90 9343.7(7) 2 1.744 7.432 4620 102824 8849 8369 0.029 463 0.039 0.106 1.033 −0.83 0.89

8

C120H166Cu6O89U10 5794.07 triclinic P1̅ 17.7344(7) 19.4751(5) 27.1156(11) 83.831(3) 87.186(2) 82.214(2) 9219.4(6) 2 2.087 9.512 5384 439080 34937 23313 0.069 2053 0.061 0.187 1.027 −2.87 3.48

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Complex 6. The three solvent water molecules were given partial occupancy factors in order to retain acceptable displacement parameters, and their hydrogen atoms were not found. As in 5, the hydrogen atom necessarily retained by one carboxylic function for charge equilibrium (and probably disordered) has not been found. Some voids in the lattice indicate the presence of other, unresolved water solvent molecules. Complex 7. Three THF solvent molecules were given 0.5 occupancy factors in order to retain acceptable displacement parameters, and restraints on bond lengths, angles and displacement parameters had to be applied for some atoms of these molecules. Neither the hydrogen atoms of the solvent water molecules, nor that necessarily retained by one carboxylic acid group for charge equilibrium have been found. Complex 8. The crystal used was merohedrally twinned with the 2fold axis parallel to [11̅0] as a twin element. The space group I4 being chiral, the volume fractions of the other possible components resulting from inversion twinning were also refined. Some solvent water molecules were given partial occupancy parameters in order to retain acceptable displacement parameters. The hydrogen atoms bound to oxygen atoms were not found. Large voids in the lattice indicate that additional, and probably highly disordered, solvent water molecules must be present. However, the residual density being quite small, the refinement could not be improved significantly by using the SQUEEZE software. Complex 9. Restraints on bond lengths had to be applied for the atoms of one very badly resolved tricarboxylate anion, and restraints on displacement parameters were applied for the atoms of this molecule and also for some other atoms which became exceedingly anisotropic, possibly indicating unresolved disorder. The hydrogen atoms bound to oxygen atoms were not found. Large voids in the lattice indicate that additional, and probably highly disordered, solvent water molecules must be present. The refinement could not be improved significantly by using the SQUEEZE software. Crystal data and structure refinement parameters are given in Table 1. The molecular plots were drawn with ORTEP-318 and the polyhedral representations with VESTA.19 The topological analyses were done with TOPOS.20

and under the present conditions, no crystalline material was obtained in the absence of such additional cations. In contrast to NMP, none of the present solvents is coordinated to uranyl ions in the final compounds (however, THF is bound to CuII cations in complex 7). It has been noted previously that the use of NMP seemed to provide a new way for avoiding the formation of oxoor hydroxo-bridged uranyl-containing oligomers or polymers which are a frequent outcome of hydrolysis.3,5 In the present series, compounds 3 and 9, obtained from methanol- or THFcontaining solutions, respectively, contain hydroxo ligands. Esterification of one carboxylic group by reaction with methanol occurred during the synthesis of complex 3, which thus contains the monoester derivative MeL2−, with the effect of reducing the highest possible ligand denticity. Crystal Structures. The linear uranyl ion coordination environment is much constrained geometrically, with four to six donor atoms located in the equatorial plane (much less frequently three or seven), and compounds 1−9 do not depart from this trend, with uranium atoms either in square (4), pentagonal (8), hexagonal (1 and 2), or both pentagonal and hexagonal (3, 5−7, and 9) bipyramidal environments. The U−O bond lengths in this series are unexceptional and will only be briefly noted. Two modes of chelation of the uranyl ion by the present ligand were observed in the previously reported structures,5 which have been denoted mode 1 when chelation involves the two oxygen atoms of one carboxylate group and mode 2 when oxygen atoms from two carboxylate groups are involved. The coordination modes of the tricarboxylic/ate ligands encountered in complexes 1−9 are represented in Scheme 1. Complex [UO2(LH2)2(H2O)2]·2H2O (1) was obtained under hydrothermal conditions. It is the only complex in this series to be mononuclear, and it is also the one in which the deprotonation degree of the tricarboxylic acid is the smallest. The structure is centrosymmetric, with uranyl chelated in mode 1 by two LH2− ligands and bound to two water molecules (Figure 1), and the arrangement of the ligands around the metal ion is a very common one, similar for example to that found in the Cambridge Structural Database (CSD, Version 5.34) 21 for the UO2(NO3)2(H2O)2 motif or in the dihydrated complexes with various monocarboxylate ligands. The LH2− ligand in 1 is in the chair conformation with all carboxylic/ate groups in an axial position. The cyclohexane mean plane is nearly perpendicular to the mean uranyl equatorial plane, and one carboxylic group of each ligand is located on each side of the latter plane. The neutral molecules are linked to one another, and to the water solvent molecules, by hydrogen bonding, and there is also one intramolecular hydrogen bond between each aqua ligand and one carboxylic group. Complex 2, [Hbipy][UO2(L)]·0.5H2O·0.25THF, was crystallized in water/THF, in the presence of manganese nitrate and 2,2′-bipyridine. Only the latter is present as a counterion in the final compound, a not very frequent occurrence in uranyl− organic assemblies.2b,3a,22 The eight-coordinated uranium atom is chelated in mode 1 by three carboxylate groups from three different ligands (Figure 2), with U−O(carboxylate) bond lengths in the range 2.450(2)−2.520(2) Å [average 2.47(2) Å]. The L3− ligand is in the chair conformation with all carboxylate groups in an equatorial position, as previously found for a similarly tris-chelating L3− ligand in [(UO2)3(L)2(NMP)2(H2O)]·2H2O.5 This divergent, tris-chelated coordination mode results in the formation of a 2D assembly parallel to the bc plane, with the total point (Schläfli) symbol {63} (all nodes

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RESULTS AND DISCUSSION Synthesis. All complexes were synthesized under solvohydrothermal conditions at 140 °C (a value in the middle part of the range of temperatures usually used in mild hydrothermal methods), except for 1, which was obtained from pure water at the same temperature. The crystals of all compounds were grown during the heating phase (not upon cooling), and their presence in the glass vials was checked visually (an advantage of this setup over the widely used Parr bombs). Among all the organic solvents which have been tested, only tetrahydrofuran, methanol, and ethanol allowed the isolation of crystalline materials, in addition to acetonitrile and NMP, as reported previously.5 However, in contrast to the results obtained with the latter solvents, all of the present complexes crystallized in very low yields, precluding any characterization apart from crystallographic. Moreover, crystals of complexes 8 and 9 grow reproducibly from the same solution (and they differ only slightly by their appearance, both having a platelet morphology). Attempts have been made to increase the yields through more prolonged heating periods or, in some cases, by changing the concentration or stoichiometry of the reactants, but they were unsuccessful. All complexes were obtained in the presence of additional metal ions, either MnII (2 and 3), NiII (1 and 6), CuII (5 and 7− 9), or TbIII (4), which were added so as to possibly increase the dimensionality of the assemblies formed, as often observed,1c but only in the cases of complexes 4 and 7−9 is the extra metal present in the final compound. However, with the solvents used 2668



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Scheme 1. Coordination Modes of the Tricarboxylic/ate Ligands in Complexes 1−9a

a

All functional groups are axial, except in complex 2, in which they are all equatorial.

Figure 2. Top: View of complex 2. Displacement ellipsoids are drawn at the 50% probability level. Counterions, solvent molecules, and hydrogen atoms are omitted. Symmetry codes: i = x, 1 − y, z − 1/2; j = 3/2 − x, 1/ 2 − y, z − 1/2; k = x, 1 − y, z + 1/2; l = 3/2 − x, 1/2 − y, z + 1/2. Middle: View of the 2D assembly. Bottom: View of the packing with sheets viewed edge-on. Solvent molecules and hydrogen atoms are omitted. Uranium coordination polyhedra are shown in the last two views.

Figure 1. View of complex 1. Displacement ellipsoids are drawn at the 30% probability level. Solvent molecules and carbon-bound hydrogen atoms are omitted. Hydrogen bonds are drawn as dashed lines. Symmetry code: i = −x, −y, 1 − z.

uranyl ions through three carboxylate groups in the 1,3,5 positions on the cyclohexane ring, which are all equatorial, while the lanthanide cation is bound to an axial carboxylate group. Other examples of this arrangement are the complexes [Hbipy][UO2(Hcbtc)]·1.5H2O and [Ni(bipy)3][UO2(Hcbtc)]2·5H2O (H4cbtc = all-trans isomer of 1,2,3,4-

trigonal). A similar topology is found, for example, in the complexes [UO2Ln(Hchhc)(H2O)7]·H2O (Ln = Pr, Eu, Tb, Er), in which H6chhc is all-cis 1,2,3,4,5,6-cyclohexanehexacarboxylic acid;23 in this complex, the (Hchhc)5− ligand chelates three 2669



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cyclobutanetetracarboxylic acid), in which only three functional groups of the ligand are coordinated.2b,c The layers in compound 2 have a corrugated shape, with methyl groups sticking out on both sides, and they are packed so as to define channels parallel to the c axis in which the THF solvent molecules are located. The Hbipy+ counterions are located near the sheets, to which they are linked by hydrogen bonds [N1···O3 2.823(4) Å, N1−H···O3 162°]. The sheets are however linked to one another by hydrogen bonds mediated by the solvent water molecules. When the reaction giving complex 2 is performed in methanol instead of THF, the outcome is completely different since the triacid reacts with the solvent to give the monoester derivative. The asymmetric unit in the structure of the resulting complex, [(UO2)3(MeL)2(OH)2(H2O)]·8MeOH (3), corresponds to half the formula unit, with three crystallographically independent uranyl ions in different environments (Figure 3). The eightcoordinated atom U1, located on a 2-fold rotation axis (Wyckoff position 4g) is chelated by two ligands in mode 1 and is also bound to two μ3-hydroxo anions (O11 and its symmetry equivalent, each of them disordered over two positions, see Experimental Section). The seven-coordinated atom U2, located on a mirror plane (site 4i), is chelated by two ligands in mode 2 (atoms O5 and O7 and their symmetry equivalents) and is bound to one μ3-hydroxo anion. Finally, the seven-coordinated atom U3, located on a 2-fold rotation axis (site 4h), is bound to two monodentate carboxylate groups (O8 and its symmetry equivalent), to two μ2-hydroxo anions (O12 and its symmetry equivalent) and one water molecule (O13). The U1−O(chelating carboxylate) and the U2,3−O(monodentate carboxylate) bond lengths [average 2.55(4) and 2.36(3) Å, respectively] are unexceptional. The MeL2− ligand, in the chair conformation with the three functional groups in axial position, connects three metal cations, with one carboxylate group chelating and bridging, and the other bridging bidentate. Atoms U1 and U2 and their symmetry equivalents through the 2-fold rotation axis and mirror plane form a tetranuclear subunit held by two μ3-hydroxo anions. This motif is frequently found with μ3-oxo anions in uranyl structural chemistry.24 For charge equilibrium, it has been assumed here that O11 corresponds to a hydroxo anion, but an alternative possibility would be to consider O11 as an oxo anion, the missing proton being located on one of the two carboxylate groups; the disorder present prevents an unambiguous assignment on geometrical grounds. Two μ2hydroxo anions connect U3 and its symmetry equivalent to give a dinuclear unit with no common donor atom with the tetranuclear one. Both subunits are assembled into a planar, ribbon-shaped one-dimensional polymer directed along the c axis. When the packing is viewed with the chains end-on, the central row of uranyl species appears to be surrounded by the carbon parts of the ligands pointing out over and below the two edges, thus defining a roughly rectangular section. Channels with a section of ∼12 Å × ∼5 Å are formed between the chains, and they are occupied by the very disordered solvent molecules (see Experimental Section). The complex [UO2Tb{(L)2H}(H2O)2] (4) pertains to the growing family of heterometallic uranyl−lanthanide species.23,25 The asymmetric unit contains half the formula unit, the uranium and terbium atoms being located on an inversion center (site 4a) and on a 2-fold rotation axis (site 4e), respectively. Unusually in the present series, uranium is hexa-coordinated, being bound to two monodentate carboxylate oxygen atoms and their images through the inversion center (Figure 4). As expected, the U− O(carboxylate) bond lengths, 2.266(3) and 2.265(3) Å, are

Figure 3. Top: View of complex 3. Displacement ellipsoids are drawn at the 30% probability level. Solvent molecules and carbon-bound hydrogen atoms are omitted. Hydrogen bonds are drawn as dashed lines. Symmetry codes: i = 1 − x, y, 2 − z; j = 1 − x, 1 − y, 2 − z; k = x, 1 − y, z; l = 1 − x, y, 1 − z; m = 1 − x, 1 − y, 1 − z. Middle: View of the 1D assembly. Bottom: View of the packing with chains viewed end-on. Solvent molecules and hydrogen atoms are omitted.

smaller than in the other cases, due to the lower coordination number. The terbium atom is bis-chelated in mode 2, and bound to two monodentate carboxylic/ate oxygen atoms and two water molecules; its eight-coordinate geometry is square antiprismatic, with the two chelating sites defining one of the square faces. Atom O7 is at hydrogen bonding distance from its image by a 2fold rotation axis and one carboxylic proton is retained, which is disordered over O7 and its image (see Experimental Section) [O7···O7i 2.445(5) Å, O7−H···O7i 150°; symmetry code: i = −x, y, 1/2 − z]; this ligand pair is denoted as {(L)2H}5−. The ligand is in the chair conformation with all carboxylic/ate groups in axial position. Both metal atoms thus connect four ligands, while the latter are bound to two uranium and two terbium atoms. A two2670



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Figure 4. Top left: View of complex 4. Displacement ellipsoids are drawn at the 50% probability level. Carbon-bound hydrogen atoms are omitted. Hydrogen bonds are drawn as dashed lines. Symmetry codes: i = −x, −y, −z; j = −x, y, 1/2 − z; k = x, −y, z − 1/2; l = x, y + 1, z; m = −x, y + 1, 1/2 − z; n = x, y − 1, z. Top right: Nodal representation of the 2D assembly. Yellow: uranium, dark blue: terbium, red: oxygen, light blue: centroid of the tricarboxylate ligand. Bottom left: View of the 2D assembly. Bottom right: View of the packing with sheets viewed edge-on.

dimensional assembly parallel to the bc plane is thus generated, with the total point symbol {42.84}{46} (first symbol for the two metal atoms and second for the carboxylate ligand); a nodal representation of this network is shown in Figure 4. The sheets consist in Tb{(L)2H}(H2O)22− anionic chains directed along the b axis, which are linked to one another by the uranyl ions. The Kitaigorodski packing index (KPI) (estimated with PLATON16) is 0.66, some voids between the layers being possibly occupied by disordered water or THF molecules. The three complexes [(UO2)8{(L)6H2}(H2O)6]·H2O (5), [(UO 2 ) 8 {(L) 6 H 2 }(H 2 O) 6 ]·3H 2 O (6), and [Cu 2 (C 2 O 4 )(bipy)2(THF)2][(UO2)8{(L)6H}(H2O)6]2·4H2O·7THF (7) all contain the same homometallic uranyl octanuclear cage-like motif which was previously found in [Ni(bipy)(H2O)4][(UO2)8(L)6(H2O)6]·H2O.5 This species is represented in Figure 5 in the case of complex 7. These complexes were obtained from a mixture of uranyl nitrate and either copper(II) nitrate in water−ethanol (5) or water−THF with the extra presence of bipy (7), or nickel(II) nitrate in water−THF (6). The octanuclear complexes in the three compounds only differ by the number of carboxylic protons retained, either one or two disordered over the six ligands, with the result that the cage species is neutral in 5 and 6, and monoanionic in 7 (while it was dianionic in the previously reported compound). In compound 7, the bimetallic copper(II) counterion contains an oxalate ligand formed in situ, a very frequent occurrence in hydrothermal syntheses of uranyl−organic species.2d,25a,c,26 Such oxalate formation was first assumed to arise from reductive coupling of

CO2 resulting from decarboxylation, but an in-depth investigation in the case of 2,3-pyrazinedicarboxylic acid (in the presence of Nd(III) cations) has shown that it proceeded through ring-opening followed by hydrolysis and oxidation,27 so that its origin in the present case cannot be assigned with any certainty. The geometry of the pseudocubic, centrosymmetric octanuclear cage has previously been described in detail,5 and no further comment will be added here. What is more important in the present context is the role of the solvent and additional species used. In the previous study, it was shown that, when uranyl nitrate was reacted with Kemp’s triacid with nickel(II) ions in water−NMP at the same temperature as that used here (140 °C), the heterometallic nanotubular species [(UO2)2Ni(L)2(H2O)4]·H2O was obtained, while, upon addition of bipy and in water−acetonitrile, the nickel ion was separated from the uranyl-containing species as a Ni(bipy)(H2O)42+ counterion. It appears here that no nanotubular complex is obtained in the presence of nickel(II) ions when NMP is changed for THF, but the neutral uranyl-containing cage 6, devoid of both nickel ions and THF (however, since the nanotubular species was previously found to crystallize as very thin needles, the presence of a very small, and barely detectable, amount of it in the present case cannot be ruled out absolutely). The other two compounds, 5 and 7, were obtained in the presence of copper nitrate. When bipy is present as well, and notwithstanding the different solvent, the result previously obtained with nickel is confirmed, with the unexpected oxalate-containing counterion in 7 and the associated variation in the number of carboxylic protons retained, 2671



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bound to two more carboxylate oxygen atoms from two different ligands and to a water molecule. The U−O(carboxylate) bond lengths are in the range 2.244(10)−2.370(9) Å [average 2.34(4) Å]. The copper atom is bound to two carboxylate oxygen atoms from two different ligands and two water molecules, giving a square planar environment with Cu−O bond lengths in the range 1.950(10)−1.978(10) Å, and it makes two longer axial contacts with two uranyl oxo groups [Cu−O1j 2.511(10) Å, Cu−O3 2.598(10) Å], with no significant lengthening of the corresponding U−O bonds. Such so-called cation−cation interactions involving d-block metal ions are frequently found in uranyl compounds.1,2a,3b,28 The L3− ligands are in the chair conformation with all carboxylate groups axial, as in the octanuclear cages. Both uranium atoms are bound to three ligands and the copper atom is bound to only two, while L3− connects three uranium and one copper atoms, as evidenced in the nodal representation of Figure 7, in which it appears that copper atoms are not topologically necessary for the formation of the cyclic species. The corresponding point symbol is {42.6}2{44.62}2{4} (successive symbols for uranium atoms, L3− anions and copper atoms). This is only the third molecular uranyl-based metallacyclic system, after the homometallic tri- and tetranuclear rings obtained with (2R,3R,4S,5S)-tetrahydrofurantetracarboxylic acid,7c and iminodiacetate-containing hexameric rings, which assemble into nanotubes.12c The metallacycle in 8 has external and internal diameters of ∼19 and ∼5 Å, respectively (the free internal diameter being thus ∼2.3 Å), and its height along the central axis is ∼11.5 Å. The water molecules bound to copper atoms protrude in the internal space, which is thus hydrophilic, while the ring is covered on the outside by the cyclohexane rings and methyl groups of the ligands, such a hydrophobic coating having been found previously in the nanotubular and octanuclear species.5 The particular shape of the L3− ligand, with the three functional groups pointing on the same side of the cyclohexane ring, is obviously conducive to the formation of closed species with hydrophobic parts segregated on the external surface, and this may be important for the formation of such assemblies, as previously suggested in the case of nanotubular compounds based on uranyl phosphonates.10a,b When viewed perpendicular to the main axis, complex 8 displays a central plane occupied by the copper atoms, surrounded by two planes containing the uranyl ions (U1 and its symmetry equivalents in one plane and U2 and its symmetry equivalents in the other). Each copper atom connects one uranyl ion in one plane to one in the other through oxo bonding, which gives four (UO2)2Cu trinuclear subunits arranged in helix geometry to give the dodecanuclear ring. The molecules are stacked so as to form channels centered on the 4fold rotation axes, as well as channels between the molecules, with a diameter of ∼6 Å. Channels are also observed in the transverse direction, along the a and b axes, with a dimension of ∼6 Å × 6 Å. The latter free spaces are occupied by the solvent water molecules, only part of which have probably been found (see Experimental Section). Overall, the solvent-occupied and free spaces are very large, since the KPI for the packing of complex molecules alone is 0.48 only. The asymmetric unit in the hexadecanuclear complex 9 corresponds to one formula unit and, with 225 non-hydrogen atoms, this assembly is a fairly large one. Although the complex does not possess any crystallographic symmetry element, it admits a 2-fold rotation axis of pseudosymmetry, perpendicular to the plane of the polyhedral representations in Figure 8 (this axis is not valid however for the copper coordination polyhedra; see below). If the ligands are disregarded, the metal atoms alone

Figure 5. Top: View of complex 7. Displacement ellipsoids are drawn at the 30% probability level. Only one of the two crystallographically independent octanuclear cages is represented. The counterion, solvent molecules, and hydrogen atoms are omitted. The octanuclear motif is analogous to those in complexes 5 and 6. Symmetry code: i = 1 − x, 2 − y, 1 − z. Bottom: View of the packing with solvent molecules and hydrogen atoms omitted. The uranium coordination polyhedra are in yellow and those of copper are in blue.

as the only differences. No nanotubular species could be obtained up to now with copper(II) ions; no uranyl-containing crystalline material could be isolated when nickel is replaced by copper in water−NMP, and, among the organic solvents which were tested, ethanol only gave crystals of the octanuclear complex 5. However, when the reaction is carried on in water−THF, green crystals of two quite remarkable uranyl−copper heterometallic complexes can be obtained. Crystals of the two complexes [(UO2)8Cu4(L)8(H2O)16]· 9H2O (8) and [(UO2)10Cu6(L)10(OH)2(H2O)7] (9) have reproducibly been found to grow from the same solutions, and both are neutral, polynuclear molecular species. Complex 8 is not a cage-like complex as 5−7 or 9 (see below), but a metallacycle which is centered on a 4-fold rotation axis (Figure 6). The asymmetric unit thus contains one-fourth the formula unit. Both uranium atoms are chelated by one L3− ligand in mode 2 and 2672



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Figure 6. Top: View of the metal ions environment in complex 8 (left) and view of the dodecanuclear ring (right). Displacement ellipsoids are drawn at the 30% probability level. Symmetry codes: i = 2 − y, x, z; j = y, 2 − x, z; k = 2 − x, 2 − y, z. Bottom: Two views of the dodecanuclear ring with the uranium coordination polyhedra in yellow and those of copper in blue. Hydrogen atoms are omitted in all views.

other 4 are assembled into two edge-sharing dinuclear subunits. Four different uranyl coordination modes are found. The eightcoordinated atoms U1 and U3 are chelated by two ligands in mode 1 and bound to two more oxygen atoms from two ligands. All the other uranium atoms are seven-coordinated; atoms U2, U4, U6, and U8 are doubly chelated in mode 2 and bound to one more carboxylate; atoms U5 and U7 are chelated in both modes 1 and 2, and bound to one more oxygen atom; and atoms U9 and U10 are chelated in mode 2 and bound to three oxygen atoms from three other ligands. There is one group of five, bis(μ3hydroxo)-bridged copper atoms in one-half-complex, and only one atom in the other half. Bridging of copper atoms by μ3hydroxo anions is extremely common and often gives polymeric material, but isolated pentanuclear species similar to the present one have been reported.29 The four atoms located at the corners of this pentanuclear subunit (Cu2−Cu5) define a plane with a root-mean-square (rms) deviation of 0.02 Å, with respect to which the central copper atom (Cu1) is displaced by 1.545(2) Å

admit two planes of pseudomirror symmetry which intersect along the former axis (approximate C2v point symmetry). It is convenient for clarity purposes to separate the whole unit into two halves along the axis of pseudosymmetry, and these are shown in Figure 8. All the L3− ligands are in chair conformation, with all-axial carboxylate groups and all oxygen atoms coordinated and, as in the previous complexes, the assembly displays hydrophobic groups on the outside. In contrast to complexes 1−8, in each of which only one coordination mode of the ligand is present, four different coordination modes are found in 9, three being present twice and the last four times in the asymmetric unit. While the number of coordinated metal atoms for each ligand is in the range 1−4 in the previous complexes, it is in the range 3−6 in 9, with all oxygen atoms involved. One of the coordination modes present displays tris-chelation in mode 2, which was previously found in a 1D polymer,5 and that with the highest nuclearity is tris(bridging bidentate). Among the 10 uranyl ions, 6 have isolated coordination polyhedra, while the 2673



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contacts for atoms Cu3 and Cu5 are with different oxo groups in the two structures. Figure 8 thus displays the set of copper coordination polyhedra found in one particular crystal structure, slight variations being possible in this respect. These five copper atoms appear to be nestled in the cavity of the uranyl-based cage, while the last copper atom, Cu6, located in the other halfmolecule, is bound to two carboxylate oxygen atoms and three water molecules (one of them pointing toward the center of the cavity), and it covers the cage as a lid. The internal cavity has a size of ∼10 Å × ∼7 Å × ∼4 Å, and its small available height (∼1.3 Å along the pseudosymmetry axis) precludes solvent inclusion (the external dimensions measured through the approximate barycenter are in the range ∼16−18 Å). It is notable that, as in complex 8, the copper atoms are not topologically necessary to the formation of the cage, as it appears in the nodal representation of Figure 7.

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CONCLUSIONS

In a previous work, it was shown that Kemp’s triacid was a very versatile ligand for the uranyl ion, since changing the organic solvent used in solvo-hydrothermal reactions gave different 1D polymers, while addition of nickel(II) cations, with or without 2,2′-bipyridine, permitted isolation of an octanuclear cage or a nanotubular assembly. In the present work, different experimental conditions were tested, with various additional metal cations and solvents, and the wide range of architectures obtained confirm the extreme sensitivity of this system upon these conditions. While the synthesis under purely hydrothermal conditions only results in monodeprotonation of the triacid and formation of a mononuclear complex, 1D or 2D assemblies were obtained in the presence of manganese nitrate (with or without bipy) or terbium nitrate, in water−THF or water−methanol. Octanuclear cages similar to that previously described were obtained from several experiments in water−THF or water− ethanol. When the reaction is performed in the presence of copper nitrate and in water−THF, instead of the octanuclear cage obtained with nickel cations in the same conditions, a mixture of two neutral, heterometallic molecular species was produced. One of these complexes is a dodecanuclear metallacycle (8 uranyl and 4 copper cations) and the other a hexadecanuclear cage (10 uranyl and 6 copper cations). In both of them, the uranyl ions are topologically sufficient to ensure the formation of the closed species, and the hydrated copper cations are for the most part embedded in the cavities formed. In all of these nanotubular, cyclic or cage-like species, the ligand is in the chair conformation with all carboxylic/ate groups axial. This is not always the case in the polymeric species, since the carboxylate groups are equatorial when the ligand is trischelating in mode 1, as found in one of the present 2D compounds and in one of the 1D polymers previously reported.5 Much variety in the coordination mode is observed, with the number of bound metal ions being one at the lowest and six at the highest, with the occurrence of two different chelating modes, as well as monodentate and bridging bidentate coordinations. The three-pronged, curved shape associated with the axial position of the functional groups is particularly conducive to the formation of closed species, with these three groups being moderately divergent from one another, and all directed away from the hydrophobic part of the ligand, which is thus segregated outside.

Figure 7. Nodal representation of the dodecanuclear ring in 8 (top) and the hexadecanuclear cage in 9 (bottom). Yellow: uranium, dark blue: copper, red: oxygen, blue: centroid of the tricarboxylate ligand. Cation− cation interactions are omitted in 8.

and the two bridging oxygen atoms by only 0.196(8) and 0.245(8) Å. Each of these five copper atoms is also bound to two carboxylate oxygen atoms from two L3− ligands, and the four lateral ones have also a water ligand. This would give a square planar geometry for all, but for the presence of longer axial contacts with uranyl oxo groups in the range 2.404(8)−2.694(9) Å (the shorter value for the central atom Cu1), which gives elongated square pyramidal environments. Curiously, these axial contacts do not admit the approximate symmetry elements indicated above, and the polyhedra are arranged in a somewhat irregular way. However, data recorded on a second crystal show that these axial distances for atoms Cu3, Cu4, and Cu5, which are close to two oxo groups, are somewhat variable and the shortest 2674



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Figure 8. Top: View of the hexadecanuclear cage in complex 9 with displacement ellipsoids drawn at the 20% probability level (left), and with the uranium coordination polyhedra in yellow and those of copper in blue (right). Bottom: Views of the two halves of the hexadecanuclear cage. Hydrogen atoms are omitted in all views.

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ASSOCIATED CONTENT

S Supporting Information *

(1) For an overview of UOFs, see: (a) Cahill, C. L.; de Lill, D. T.; Frisch, M. CrystEngComm 2007, 9, 15. (b) Cahill, C. L.; Borkowski, L. A. In Structural Chemistry of Inorganic Actinide Compounds; Krivovichev, S. V., Burns, P. C., Tananaev, I. G., Eds.; Elsevier: Amsterdam, Oxford, 2007; Chapter 11. (c) Wang, K. X.; Chen, J. S. Acc. Chem. Res. 2011, 44, 531. (d) Andrews, M. B.; Cahill, C. L. Chem. Rev. 2013, 113, 1121. (e) Loiseau, T.; Mihalcea, I.; Henry, N.; Volkringer, C. Coord. Chem. Rev. 2014, 266−267, 69. (2) See, for example: (a) Olchowka, J.; Falaise, C.; Volkringer, C.; Henry, N.; Loiseau, T. Chem.Eur. J. 2013, 19, 2012. (b) Thuéry, P. Eur. J. Inorg. Chem. 2013, 4563. (c) Thuéry, P. CrystEngComm 2013, 15, 6533. (d) Thuéry, P.; Rivière, E. Dalton Trans. 2013, 42, 10551. (3) (a) Thuéry, P.; Harrowfield, J. Cryst. Growth Des. 2014, 14, 1314. (b) Thuéry, P.; Harrowfield, J. CrystEngComm 2014, 16, 2996. (4) Kemp, D. S.; Petrakis, K. S. J. Org. Chem. 1981, 46, 5140.

Tables of crystal data, atomic positions and displacement parameters, anisotropic displacement parameters, and bond lengths and bond angles in CIF format. This material is available free of charge via the Internet at http://pubs.acs.org/.

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REFERENCES

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest. 2675



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(5) Thuéry, P. Cryst. Growth Des. 2014, 14, 901. (6) (a) Okui, Y.; Catusanu, F. A.; Kubota, R.; Kure, B.; Nakajima, T.; Tanase, T.; Kajiwara, T.; Mikuriya, M.; Miyasaka, H.; Yamashita, M. Eur. J. Inorg. Chem. 2011, 4325. (b) Takemura, Y.; Okui, Y.; Kure, B.; Nakajima, T.; Tanase, T.; Mikuriya, M.; Takahashi, M. Inorg. Chim. Acta 2011, 379, 100. (7) (a) Thuéry, P.; Nierlich, M.; Baldwin, B. W.; Komatsuzaki, N.; Hirose, T. J. Chem. Soc., Dalton Trans. 1999, 1047. (b) Thuéry, P.; Masci, B. Supramol. Chem. 2003, 15, 95. (c) Thuéry, P.; Villiers, C.; Jaud, J.; Ephritikhine, M.; Masci, B. J. Am. Chem. Soc. 2004, 126, 6838. (d) Thuéry, P.; Masci, B. Cryst. Growth Des. 2008, 8, 3430. (e) Thuéry, P. Cryst. Growth Des. 2009, 9, 4592. (8) (a) Burns, P. C.; Kubatko, K. A.; Sigmon, G.; Fryer, B. J.; Gagnon, J. E.; Antonio, M. R.; Soderholm, L. Angew. Chem., Int. Ed. 2005, 44, 2135. (b) Qiu, J.; Burns, P. C. Chem. Rev. 2013, 113, 1097 and references therein. (9) Pasquale, S.; Sattin, S.; Escudero-Adán, E. C.; Martínez-Belmonte, M.; de Mendoza, J. Nat. Commun. 2012, 3, 785. (10) (a) Poojari, D. M.; Grohol, D.; Clearfield, A. Angew. Chem., Int. Ed. 1995, 34, 1508. (b) Aranda, M. A. G.; Cabeza, A.; Bruque, S.; Poojari, D. M.; Clearfield, A. Inorg. Chem. 1998, 37, 1827. (c) Adelani, P. O.; Albrecht-Schmitt, T. E. Angew. Chem., Int. Ed. 2010, 49, 8909. (d) Adelani, P. O.; Albrecht-Schmitt, T. E. Inorg. Chem. 2011, 50, 12184. (e) Wu, S.; Wang, S.; Diwu, J.; Depmeier, W.; Malcherek, T.; Alekseev, E. V.; Albrecht-Schmitt, T. E. Chem. Commun. 2012, 48, 2334. (11) (a) Krivovichev, S. V.; Kahlenberg, V.; Tananaev, I. G.; Kaindl, R.; Mersdorf, E.; Myasoedov, B. F. J. Am. Chem. Soc. 2005, 127, 1072. (b) Albrecht-Schmitt, T. E. Angew. Chem., Int. Ed. 2005, 44, 4836. (c) Krivovichev, S. V. Eur. J. Inorg. Chem. 2010, 2594. (12) (a) Thuéry, P. Inorg. Chem. Commun. 2008, 11, 616. (b) Mihalcea, I.; Henry, N.; Loiseau, T. Cryst. Growth Des. 2011, 11, 1940. (c) Unruh, D. K.; Gojdas, K.; Libo, A.; Forbes, T. Z. J. Am. Chem. Soc. 2013, 135, 7398. (13) Hooft, R. W. W. COLLECT; Nonius BV: Delft, The Netherlands, 1998. (14) Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307. (15) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112. (16) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7. (17) (a) Tauer, K. J.; Lipscomb, W. N. Acta Crystallogr. 1952, 5, 606. (b) Kirchner, M. T.; Das, D.; Boese, R. Cryst. Growth Des. 2008, 8, 763. (18) Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565. (19) Momma, K.; Izumi, F. J. Appl. Crystallogr. 2008, 41, 653. (20) (a) Blatov, V. A.; Shevchenko, A. P.; Serezhkin, V. N. J. Appl. Crystallogr. 2000, 33, 1193. (b) Blatov, V. A.; O’Keeffe, M.; Proserpio, D. M. CrystEngComm 2010, 12, 44. (21) (a) Allen, F. H. Acta Crystallogr., Sect. B 2002, 58, 380. (b) Bruno, I. J.; Cole, J. C.; Edgington, P. R.; Kessler, M.; Macrae, C. F.; McCabe, P.; Pearson, J.; Taylor, R. Acta Crystallogr., Sect. B 2002, 58, 389. (22) (a) Thuéry, P. Inorg. Chem. 2007, 46, 2307. (b) Adelani, P. O.; Albrecht-Schmitt, T. E. Inorg. Chem. 2009, 48, 2732. (23) Thuéry, P. Cryst. Growth Des. 2010, 10, 2061. (24) See, for example: (a) Van den Bossche, G.; Spirlet, M. R.; Rebizant, J.; Goffart, J. Acta Crystallogr., Sect. C 1987, 43, 837. (b) Turpeinen, U.; Hämäläinen, R.; Mutikainen, I.; Orama, O. Acta Crystallogr., Sect. C 1996, 52, 1169. (c) Thuéry, P.; Nierlich, M.; Souley, B.; Asfari, Z.; Vicens, J. J. Chem. Soc., Dalton Trans. 1999, 2589. (d) Yu, Z. T.; Li, G. H.; Jiang, Y. S.; Xu, J. J.; Chen, J. S. Dalton Trans. 2003, 4219. (e) Crawford, M. J.; Mayer, P.; Nöth, H.; Suter, M. Inorg. Chem. 2004, 43, 6860. (f) Harrowfield, J. M.; Skelton, B. W.; White, A. H. C. R. Chim. 2005, 8, 169. (g) Charushnikova, I. A.; Krot, N. N.; Polyakova, I. N.; Makarenkov, V. I. Radiokhimiya 2005, 47, 219. (h) Borkowski, L. A.; Cahill, C. L. Cryst. Growth Des. 2006, 6, 2248. (i) Hennig, C.; Servaes, K.; Nockemann, P.; Van Hecke, K.; Van Meervelt, L.; Fluyt, L.; Wouters, J.; Görller-Walrand, C.; Van Deun, R. Inorg. Chem. 2008, 47, 2987. (j) Thuéry, P. Cryst. Growth Des. 2008, 8, 4132. (k) Rodríguez-Diéguez, A.; Mota, A. J.; Seco, J. M.; Palacios, M. A.; Romerosa, A.; Colacio, E. Dalton Trans. 2009, 9578. (l) Villiers, C.; Thuéry, P.; Ephritikhine, M. Polyhedron 2010, 29, 1593. (m) Thuéry, P. Cryst. Growth Des. 2011, 11, 2606. (n) Thuéry, P. Cryst. Growth Des. 2012, 12, 499.

(25) (a) Thuéry, P. CrystEngComm 2008, 10, 1126. (b) Thuéry, P. Inorg. Chem. 2009, 48, 825. (c) Thuéry, P. CrystEngComm 2009, 11, 2319. (d) Arnold, P. L.; Hollis, E.; White, F. J.; Magnani, N.; Caciuffo, R.; Love, J. B. Angew. Chem., Int. Ed. 2011, 50, 887. (e) Diwu, J.; Wang, S.; Good, J. J.; DiStefano, V. H.; Albrecht-Schmitt, T. E. Inorg. Chem. 2011, 50, 4842. (f) Knope, K. E.; de Lill, D. T.; Rowland, C. E.; Cantos, P. M.; de Bettencourt-Dias, A.; Cahill, C. L. Inorg. Chem. 2012, 51, 201. (g) Volkringer, C.; Henry, N.; Grandjean, S.; Loiseau, T. J. Am. Chem. Soc. 2012, 134, 1275. (h) Thuéry, P. CrystEngComm 2012, 14, 3363. (i) Thuéry, P. CrystEngComm 2012, 14, 6369. (j) Mihalcea, I.; Volkringer, C.; Henry, N.; Loiseau, T. Inorg. Chem. 2012, 51, 9610. (k) Arnold, P. L.; Hollis, E.; Nichol, G. S.; Love, J. B.; Griveau, J. C.; Caciuffo, R.; Magnani, N.; Maron, L.; Castro, L.; Yahia, A.; Odoh, S. O.; Schreckenbach, G. J. Am. Chem. Soc. 2013, 135, 3841. (26) See, for example: (a) Li, X.; Cao, R.; Sun, D.; Shi, Q.; Bi, W.; Hong, M. Inorg. Chem. Commun. 2003, 6, 815. (b) Frisch, M.; Cahill, C. L. Dalton Trans. 2005, 1518. (c) Li, B.; Gu, W.; Zhang, L. Z.; Qu, J.; Ma, Z. P.; Liu, X.; Liao, D. Z. Inorg. Chem. 2006, 45, 10425. (d) Thuéry, P. Polyhedron 2007, 26, 101. (e) Frisch, M.; Cahill, C. L. J. Solid State Chem. 2007, 180, 2597. (f) Knope, K. E.; Cahill, C. L. Inorg. Chem. 2007, 46, 6607. (g) Ziegelgruber, K. L.; Knope, K. E.; Frisch, M.; Cahill, C. L. J. Solid State Chem. 2008, 181, 373. (h) Thuéry, P. CrystEngComm 2008, 10, 808. (i) Thuéry, P. CrystEngComm 2010, 12, 1905. (j) Rowland, C. E.; Cahill, C. L. Inorg. Chem. 2010, 49, 6716. (k) Thuéry, P. Inorg. Chem. 2011, 50, 1898. (l) Andrews, M. B.; Cahill, C. L. CrystEngComm 2011, 13, 7068. (27) Knope, K. E.; Kimura, H.; Yasaka, Y.; Nakahara, M.; Andrews, M. B.; Cahill, C. L. Inorg. Chem. 2012, 51, 3883. (28) (a) Siegel, S.; Hoekstra, H. R. Acta Crystallogr., Sect. B 1968, 24, 967. (b) Legros, J. P.; Jeannin, Y. Acta Crystallogr., Sect. B 1975, 31, 1133. (c) Locock, A. J.; Burns, P. C. Can. Mineral 2003, 41, 489. (d) Chen, W.; Yuan, H. M.; Wang, J. Y.; Liu, Z. Y.; Xu, J. J.; Yang, M.; Chen, J. S. J. Am. Chem. Soc. 2003, 125, 9266. (e) Shvareva, T. Y.; Albrecht-Schmitt, T. E. Inorg. Chem. 2006, 45, 1900. (f) Arnold, P. L.; Patel, D.; Blake, A. J.; Wilson, C.; Love, J. B. J. Am. Chem. Soc. 2006, 128, 9610. (g) Arnold, P. L.; Patel, D.; Wilson, C.; Love, J. B. Nature 2008, 451, 315. (h) Thuéry, P. Inorg. Chem. Commun. 2009, 12, 800. (i) Alsobrook, A. N.; Hauser, B. G.; Hupp, J. T.; Alekseev, E. V.; Depmeier, W.; Albrecht-Schmitt, T. E. Chem. Commun. 2010, 46, 9167. (j) Alsobrook, A. N.; Hauser, B. G.; Hupp, J. T.; Alekseev, E. V.; Depmeier, W.; Albrecht-Schmitt, T. E. Cryst. Growth Des. 2011, 11, 1385. (29) (a) Meenakumari, S.; Lakshminarayanan, M.; Tiwary, S. K.; Chakravarty, A. R. Inorg. Chem. 1995, 34, 5091. (b) Ghosh, S. K.; Azhakar, R.; Kitagawa, S. Chem.Asian J. 2009, 4, 870. (c) Jiang, J. C.; Chu, Z. L.; Huang, W.; Wang, G.; You, X. Z. Inorg. Chem. 2010, 49, 5897.

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