Uranyl Ion Complexation by Cucurbiturils in the Presence of Perrhenic

DOI: 10.1021/cg901121c

Uranyl Ion Complexation by Cucurbiturils in the Presence of Perrhenic, Phosphoric, or Polycarboxylic Acids. Novel Mixed-Ligand Uranyl-Organic Frameworks

2010, Vol. 10 716–725

Pierre Thuery*,† and Bernardo Masci‡ †

CEA, IRAMIS, SIS2M (CNRS URA 331), LCCEf, B^ at. 125, F-91191 Gif-sur-Yvette, France and Dipartimento di Chimica, Universit a “La Sapienza”, Box 34, Roma 62, P.le Aldo Moro 5, 00185 Roma, Italy ‡

Received September 14, 2009; Revised Manuscript Received October 26, 2009

ABSTRACT: Six novel complexes formed under hydrothermal conditions by reaction of uranium trioxide or uranyl nitrate with cucurbit[6]uril (CB6), or cucurbit[7]uril (CB7) in one case, in the presence of additional ligands, either tetrahedral oxoanions or polycarboxylic acids, have been structurally characterized. In [(UO2)2(CB6)(ReO4)4(H2O)3] 3 2HReO4 3 5H2O (1), three perrhenate ions are bound to uranyl ions and one is encapsulated in the CB6 cavity, while perrhenate acts as a counterion only in the CB7 complex [UO2(CB7)(NO3)(H2O)2](ReO4) 3 5H2O (2). 1 is a molecular complex and 2 a one-dimensional polymer. Complex 3, [UO2(H2PO4)2(H2O)]2 3 CB6 3 H3PO4 3 6H2O, obtained in the presence of orthophosphoric acid, comprises onedimensional uranyl dihydrogen phosphate chains, and the CB6 molecules are uncoordinated, as in [(UO2)4(C2O4)3(NO3)2(H2O)6] 3 CB6 3 6H2O (4), which displays an unprecedented tetranuclear uranyl oxalate moiety hydrogen bonded to the CB6 molecules. With pyrazinetetracarboxylic acid (H4PZTC), a one-dimensional polymer with alternate PZTC4- and CB6 ligands is formed, [(UO2)2(PZTC)(CB6)(H2O)2] 3 12H2O (5). Finally, the complex [(UO2)5(cit)2(CB6)(NO3)2(H2O)6] 3 7H2O (6), synthesized in the presence of citric acid (H4cit), is an intricate three-dimensional framework in which the uranyl citrate part builds a three-dimensional subunit defining cagelike spaces where the CB6 ligands are located. These results evidence the interest of cucurbiturils as structure-directing agents (complexes 3 and 4) and as auxiliary ligands in mixed-ligand uranyl-organic frameworks (5 and 6).

Introduction

Scheme 1. Cucurbit[n]urils

The complexing properties of cucurbit[n]urils (CBn, Scheme 1)1 toward f-element ions have been widely investigated in recent years. In the case of lanthanides, an extensive study of the crystal structures of the complexes formed with cucurbit[6]uril has been performed by Fedin et al., which evidenced the rich structural variety of this system.2 The actinide ions were expectedly less investigated, but the same group reported the thorium(IV) complex [Th2(CB6)Cl2(H2O)10]Cl6, in which one cation is bound to three adjacent carbonyl groups of each CB6 portal,2c and the uranyl complex [(UO2)4(μ3-O)2(μ2-Cl)4(H2O)6] 3 CB6, in which there is no uranium-carbonyl bond, with the tetranuclear uranyl complex being only hydrogen bonded to the macrocycle.3 More recently, several uranyl complexes of CBn (n = 5-8), obtained under hydrothermal conditions and displaying uranyl bonding to the carbonyl groups, have been crystallographically characterized.4-7 CB5 appeared perfectly suited to uranyl bonding by the five oxygen atoms of one portal, giving an open molecular capsule,5 whereas the other CBs are coordinated to uranyl in monodentate fashion, with two uranyl ions at most bound at each portal. Much structural variety results from the use of differing experimental conditions and, in particular, from the use of additional ligands such as sulfate4 or formate5,6 ions. Heterometallic uranyllanthanide complexes were also obtained, in which one perrhenate ion, an analogue of the radioactive pertechnetate ion, is included in the CB6 cavity.7 Further work with *To whom correspondence should be addressed. E-mail: pierre.thuery@ cea.fr. pubs.acs.org/crystal

Published on Web 11/19/2009

lanthanide ions alone has shown that encapsulation of the perrhenate ion, coordinated to the cation or not, was ubiquitous in the case of CB6 and CB7.8 It thus appeared worthwhile to examine the complexes formed by uranyl alone with CB6 or CB7 in the presence of perrhenate ions and, for comparison, other tetrahedral oxoanions such as the phosphate ion (complexes with sulfate have been described previously4). Since some of these oxoanions give rise to the formation of uranyl-containing polymers associated to CBs, it also seemed interesting to try to use polytopic carboxylic acids to generate such polymeric subunits. The syntheses and crystal structures of six complexes obtained in the course of this work are reported herein. Experimental Section Synthesis. Caution! Because uranium is a radioactive and chemically toxic element, uranium-containing samples must be handled with suitable care and protection. r 2009 American Chemical Society

Article UO2(NO3)2 3 6H2O was purchased from Prolabo, and UO3 was provided by the CEA. Perrhenic acid (76.5% solution in water) was from Acros, orthophosphoric acid (85% solution in water) from Sigma, L-(þ)-tartaric acid from Prolabo, and citric acid from Fluka. Pyrazinetetracarboxylic acid was synthesized according to a literature procedure;9 its purity was checked through a 13C NMR spectrum (50 MHz) in D2O and excess KOH, that only showed two peaks at δ 148.3 and 172.7. Cucurbit[6]uril hydrate was purchased from Fluka and cucurbit[7]uril hydrate from Aldrich. The water content in the two latter compounds is ca. 5 and 10 water molecules per cucurbituril molecule, respectively, according to the analyses provided by the seller. Elemental analyses were performed by Analytische Laboratorien GmbH at Lindlar, Germany, and Service de Microanalyse du CNRS at Gif-sur-Yvette, France. The reaction conditions used often result in the formation of insoluble powders and only in some out of many attempts with varying reactants and concentrations was it possible to get single crystals suitable for structure determination. [(UO2)2(CB6)(ReO4)4(H2O)3] 3 2HReO4 3 5H2O (1). CB6 3 5H2O (30 mg, 0.028 mmol), a 10-fold excess of UO3 (80 mg, 0.280 mmol), excess HReO4 (200 mg, 0.80 mmol), and demineralized water (1.3 mL) were placed in a 15 mL tightly closed glass vessel and heated at 180 C under autogenous pressure. Light yellow crystals of complex 1 appeared in low yield within one month. [UO2(CB7)(NO3)(H2O)2](ReO4) 3 5H2O (2). CB7 3 10H2O (10 mg, 0.007 mmol), a 10-fold excess of UO2(NO3)2 3 6H2O (35 mg, 0.070 mmol) and HReO4 (18 mg, 0.072 mmol), and demineralized water (1.7 mL) were placed in a 10 mL tightly closed glass vessel and heated at 180 C under autogenous pressure. Light yellow crystals of complex 2 were obtained in very low yield within two days. [UO2 (H2 PO4 )2 (H2 O)]2 3 CB6 3 H 3PO 4 3 6H2O (3). CB6 3 5H2O (10 mg, 0.009 mmol), a 5-fold excess of UO2(NO3)2 3 6H2O (23 mg, 0.046 mmol), a large excess of H3PO4 (500 mg, 5.10 mmol), and demineralized water (2.5 mL) were placed in a 15 mL tightly closed glass vessel and heated at 180 C under autogenous pressure. Light yellow crystals of complex 3 appeared within two days. The product was recovered after filtration and washed with water (7 mg, 36% yield based on CB6). Anal. Calcd for C36H63N24O44P5U2: C, 19.95; H, 2.93; N, 15.51. Found: C, 19.09; H, 3.13; N, 15.03%. [(UO2 )4(C 2O 4)3(NO3 )2(H2 O)6 ] 3 CB6 3 6H2 O (4). CB6 3 5H2O (20 mg, 0.018 mmol), a 4-fold excess of UO2(NO3)2 3 6H2O (36 mg, 0.072 mmol) and L-(þ)-tartaric acid (11 mg, 0.073 mmol), and demineralized water (2.5 mL) were placed in a 15 mL tightly closed glass vessel and heated at 180 C under autogenous pressure. Light yellow crystals of complex 4, comprising oxalate ligands formed in situ, were obtained within three days. The product was recovered after filtration and washed with water (23 mg, 48% yield). Anal. Calcd for C42H60N26O50U4: C, 18.82; H, 2.26; N, 13.58. Found: C, 19.05; H, 2.42; N, 12.99%. [(UO2)2(PZTC)(CB6)(H2O)2] 3 12H2O (5). CB6 3 5H2O (20 mg, 0.018 mmol), a 5-fold excess of UO2(NO3)2 3 6H2O (45 mg, 0.090 mmol), a 2-fold excess of H4PZTC (9 mg, 0.035 mmol), and demineralized water (2.5 mL) were placed in a 15 mL tightly closed glass vessel and heated at 180 C under autogenous pressure. Light yellow crystals of complex 5 were obtained in low yield within 24 h. [(UO2)5(cit)2(CB6)(NO3)2(H2O)6] 3 7H2O (6). CB6 3 5H2O (20 mg, 0.018 mmol), a 5-fold excess of UO2(NO3)2 3 6H2O (45 mg, 0.090 mmol), citric acid (4 mg, 0.021 mmol), and demineralized water (2 mL) were placed in a 15 mL tightly closed glass vessel and heated at 180 C under autogenous pressure. Light yellow crystals of complex 6 were obtained in low yield within ten days. Crystallography. The data were collected on a Nonius KappaCCD area detector diffractometer10 using graphite-monochromated Mo KR radiation (λ = 0.71073 A˚). The crystals were introduced into glass capillaries with a protecting “Paratone-N” oil (Hampton Research) coating. The unit cell parameters were determined from ten frames and then refined on all data. The data (combinations of j- and ω-scans giving complete data sets up to θ=25.7 and a minimum redundancy of 4 for 90% of the reflections) were processed with HKL2000.11 The structures were solved by Patterson map interpretation (complex 5) or by direct methods (all other compounds) with SHELXS-97, expanded by subsequent Fourier-difference synthesis, and refined by full-matrix

Crystal Growth & Design, Vol. 10, No. 2, 2010

717

least-squares on F2 with SHELXL-97.12 Absorption effects were corrected empirically with the program SCALEPACK.11 All nonhydrogen atoms were refined with anisotropic displacement parameters. The carbon-bound hydrogen atoms were introduced at calculated positions. All hydrogen atoms were treated as riding atoms with an isotropic displacement parameter equal to 1.2 times that of the parent atom. Some voids in the lattice of compounds 2-5 likely indicate the presence of other, unresolved solvent water molecules. Restraints on displacement parameters and/or bond lengths were applied for badly behaving atoms in all compounds but 5. Special details are as follows: Compound 1. The perrhenate ion containing Re2 and the water molecule containing O18 are disordered over the same uranyl ion coordination site, and both have been given an occupancy factor of 0.5. Restraints on bond lengths and displacement parameters were applied for the badly resolved, disordered perrhenate ion. The solvent water molecule containing O27 has also been given a 0.5 occupancy factor in order to retain an acceptable displacement parameter and also to account for its closeness to its image by symmetry. The hydrogen atoms bound to O9 were found on a Fourier-difference map, but not those of O18, the perrhenic acid, and the solvent water molecules. A short O 3 3 3 C contact involving an oxygen atom of the disordered perrhenate ion is likely due to the imperfect geometry of this moiety. Compound 2. The hydrogen atoms bound to oxygen atoms were not found. The highest residual electron density peak is located near the uranium atom, probably as a result of imperfect absorption corrections. The Flack parameter was refined to a value of 0.026(9). Compound 3. The free orthophosphoric acid molecule was given a 0.5 occupancy factor in order to retain acceptable displacement parameters. The hydrogen atoms of the coordinated H2PO4- group were found on a Fourier-difference map, but not those of the free H3PO4 and the water molecules. Compound 4. The hydrogen atoms bound to O14, O15, and O16 were found on a Fourier-difference map, but not those of the solvent water molecules. Compound 5. The water solvent molecules O18/O19 and O20/ O21 are too close to one another, and they have been given occupancy parameters constrained to sum to unity. The hydrogen atoms bound to oxygen atoms were found on a Fourier-difference map, except for those of the disordered water molecules. Compound 6. The water solvent molecule containing O28 was given an occupancy factor of 0.5 in order to retain an acceptable displacement parameter. The hydrogen atoms bound to oxygen atoms were found on a Fourier-difference map, except for those of O16 and O28. Crystal data and structure refinement parameters are given in Table 1, and selected bond lengths and angles in Table 2. The molecular plots were drawn with SHELXTL12 and Balls & Sticks.13

Results and Discussion Complexes 1 and 2, with CB6 and CB7, respectively, were obtained in the presence of perrhenic acid. The 4f-5f heterometallic complexes [UO2Ln(CB6)(ReO4)2(NO3)(H2O)7](ReO4)2 (Ln = Sm, Eu, Gd, Lu), previously reported and obtained under analogous conditions,7 were the second example of uranyl-lanthanide heterometallic complexes;14 they were also the first to show that ReO4- could be encapsulated in the CB6 cavity, and in addition, they displayed perrhenate coordination to both uranyl and lanthanide ions, which is quite unusual.15,16 The structures of the lanthanide complexes of CBn (n = 5, 6, 7) comprising perrhenate ions confirmed these trends in the cases n=6 and 7, whereas the size of CB5 appears too small for perrhenate inclusion.8 This was also apparent in the complex [UO2(CB5)](ReO4)2 3 2H2O, in which ReO4- is located outside the cavity (in fact, this anion was chosen in this case for its low coordinating ability, which enables uranyl chelation by five CB5 oxygen atoms).5 This phenomenon of perrhenate encapsulation is particularly

718


Thuery and Masci

Table 1. Crystal Data and Structure Refinement Details chemical formula M (g mol-1) cryst syst space group a (A˚) b (A˚) c (A˚) R (deg) β (deg) γ (deg) V (A˚3) Z T (K) Dcalcd (g cm-3) μ(Mo KR) (mm-1) F(000) reflns collcd indep reflns obsd reflns [I > 2σ(I)] Rint params refined R1 wR2 S ΔFmin (e A˚-3) ΔFmax (e A˚-3)

1

2

3

4

5

6

C36H54N24O48Re6U2 3184.29 monoclinic C2/c 24.7460(13) 14.3367(4) 23.1929(11) 90 115.689(2) 90 7415.0(6) 4 100(2) 2.852 14.224 5824 106988 7037 5769 0.040 555 0.041 0.111 1.052 -2.14 2.39

C42H56N29O30ReU 1871.39 monoclinic P21 13.7493(7) 17.5847(8) 14.0579(8) 90 94.540(3) 90 3388.2(3) 2 100(2) 1.834 4.277 1836 103535 12839 11217 0.042 930 0.072 0.195 1.027 -3.15 3.09

C36H63N24O44P5U2 2167.01 monoclinic C2/m 11.9376(10) 24.167(2) 13.0767(13) 90 110.183(5) 90 3540.9(6) 2 150(2) 2.032 4.801 2116 82130 3430 3066 0.036 271 0.050 0.141 1.130 -2.11 1.97

C42H60N26O50U4 2681.28 triclinic P1 12.3313(8) 12.4408(7) 13.9607(9) 114.175(3) 100.367(3) 94.717(4) 1892.8(2) 1 100(2) 2.352 8.657 1262 55920 7110 6005 0.067 550 0.042 0.116 1.059 -2.49 2.14

C44H64N26O38U2 2041.27 monoclinic P21/c 12.7269(5) 15.9343(7) 16.6695(4) 90 91.641(3) 90 3379.1(2) 2 100(2) 2.006 4.906 1996 99466 6398 5715 0.042 515 0.036 0.084 1.189 -1.77 1.10

C48H70N26O55U5 3081.45 monoclinic P21/c 12.5538(8) 19.1066(6) 16.7831(11) 90 95.883(3) 90 4004.4(4) 2 100(2) 2.556 10.208 2880 91769 7597 5576 0.054 610 0.042 0.094 0.997 -2.37 1.30

Table 2. Environment of the Uranium Atoms in Compounds 1-6: Selected Bond Lengths (A˚) and Angles (deg) 1

2

3

4

U-O1 U-O2 U-O3 U-O5 U-O9 U-O10 U-O14 U-O18 U-O1 U-O2 U-O3 U-O6 U-O7 U-O8 U-O90 U-O1 U-O2 U-O300 U-O6 U1-O1 U1-O2 U1-O5 U1-O7 U1-O9 U1-O100 U1-O11 U1-O12 U2-O3 U2-O4 U2-O6 U2-O8 U2-O14 U2-O15 U2-O16

1.749(8) 1.750(8) 2.385(7) 2.390(6) 2.385(8) 2.353(7) 2.56(2) 2.329(18) 1.763(9) 1.716(9) 2.402(10) 2.420(8) 2.358(12) 2.379(9) 2.418(9) 1.779(6) 2.330(6) 2.363(6) 2.448(13) 1.754(6) 1.761(6) 2.492(6) 2.458(6) 2.495(6) 2.465(6) 2.495(7) 2.527(6) 1.774(7) 1.753(7) 2.456(7) 2.433(6) 2.371(7) 2.374(6) 2.372(6)

O1-U-O2 O3-U-O5 O5-U-O9 O9-U-O10 O10-U-O14 O14-U-O3 O10-U-O18 O18-U-O3 O1-U-O2 O3-U-O8 O8-U-O6 O6-U-O90 O90 -U-O7 O7-U-O3

178.6(3) 72.1(2) 73.2(2) 74.2(3) 71.1(5) 69.8(5) 70.1(6) 70.5(6) 177.7(5) 72.9(4) 71.0(4) 69.1(4) 72.6(4) 75.5(4)

O1-U-O10 O2-U-O3000 O3000 -U-O300 O2-U-O6 O1-U1-O2 O5-U1-O7 O7-U1-O9 O9-U1-O100 O100 -U1-O11 O11-U1-O12 O12-U1-O5

179.5(4) 77.3(2) 71.5(3) 67.03(14) 179.1(3) 63.6(2) 61.33(19) 63.69(19) 61.8(2) 50.64(19) 60.46(19)

O3-U2-O4 O6-U2-O8 Ο8-U2-O14 O14-U2-O15 O15-U2-O16 Ο16-U2-O6

179.1(3) 66.2(2) 70.7(2) 75.3(2) 75.8(2) 72.0(2)

5

6

U-O1 U-O2 U-O3 U-O5 U-O7 U-O13 U-N1 U1-O1 U1-O2 U1-O6 U1-O100 U1-O13 U1-O16 U1-O19 U2-O3 U2-O4 U2-O7 U2-O1100 U2-O12 U2-O1200 U2-O17 U3-O5 U3-O8 U3-O9 U3-O18

1.766(4) 1.761(4) 2.350(4) 2.334(4) 2.357(4) 2.369(4) 2.576(4) 1.766(6) 1.748(5) 2.435(6) 2.392(6) 2.468(6) 2.469(6) 2.387(6) 1.766(6) 1.762(7) 2.412(6) 2.426(6) 2.407(6) 2.370(7) 2.328(7) 1.751(6) 2.462(6) 2.453(7) 2.472(7)

O1-U-O2 O3-U-N1 N1-U-O5 O5-U-O13 O13-U-O7 O7-U-O3

177.51(17) 63.02(13) 62.75(14) 82.39(14) 77.12(13) 74.73(12)

O1-U1-O2 O6-U1-O13 O13-U1-O100 O100 -U1-O19 O19-U1-O16 O16-U1-O6

173.1(3) 71.2(2) 75.1(2) 72.2(2) 68.4(2) 76.8(2)

O3-U2-O4 O7-U2-O12 O12-U2-O1200 O1200 -U2-O1100 O1100 -U2-O17 O17-U2-O7

176.8(3) 64.7(2) 70.0(2) 76.5(2) 75.4(2) 74.3(2)

O5-U3-O5# O8-U3-O9 O9-U3-O18 O18-U3-O8#

180 53.3(2) 64.5(2) 62.2(2)

Symmetry codes: 2: 0 = 1 - x, y þ 1/2, 2 - z; 3: 0 = 1 - x, y, -z; 00 = 1/2 - x, 1/2 - y, -z; 000 = 1/2 þ x, 1/2 - y, z; 4: 0 = -x, 2 - y, 2 - z; 6: 0 = x, 3/2 - y, z þ 1/2; 00 = 1 - x, 2 - y, -z; # = -x, 2 - y, -z.

interesting considering the analogy between this anion and the highly soluble TcO4- pertechnetate ion, present in large quantities in nuclear wastes and containing the long-lived β-emitter 99Tc (half-life 2.13 105 years). Complex 1, [(UO2)2(CB6)(ReO4)4(H2O)3] 3 2HReO4 3 5H2O, is a dinuclear species, located around a binary axis,

in which one uranyl ion is bound to each CB6 portal (Figure 1). Whereas CB6 (and also CB7 and CB8) has always been found up to now to act as a monodentate ligand toward uranyl, bidentate coordination is observed in 1, with an average U-O(carbonyl) bond length of 2.388(2) A˚, well in the range 2.337(6)-2.545(6) A˚ [mean value 2.41(7) A˚] in the

Article


719

Table 3. OH 3 3 3 O Hydrogen Bonding Geometry in Compounds 1-6: Distances (A˚) and Angles (deg)a

1 2b 3 4

5 6

O9 3 3 O9 3 3 O6 3 3 O4 3 3 O5 3 3 O14 3 O14 3 O15 3 O15 3 O16 3 O16 3 O13 3 O13 3 O17 3 O17 3 O18 3 O18 3

3 O21w0 3 O26w 3 O10 3 O7 3 O13w 3 3 O21 3 3 O23w 0 3 3 O19 O24 w 33 0 3 3 O17 3 3 O25w 3 3 O14w0 3 3 O15w 3 3 O26w 3 3 O27w 0 3 3 O160 O23 33

D3 3 3A 2.722(14) 2.632(16) 2.765(14) 2.616(10) 2.618(10) 2.608(9) 2.596(10) 2.659(8) 2.645(14) 2.660(8) 2.671(9) 2.592(6) 2.588(6) 2.608(10) 2.631(10) 3.009(9) 2.615(9)

D-H 0.83 0.80

H3 3 3A 1.89 1.84

D-H 3 3 3 A 178 170

0.93 0.95 0.83 0.92 0.79 0.92 0.93 0.92 0.87 0.86 0.82 0.90 0.81 0.90

1.71 1.80 1.85 2.04 2.01 1.77 2.06 1.76 1.74 1.96 1.81 1.78 2.21 1.75

167 142 151 117 138 158 121 168 166 128 165 156 169 161

a The oxygen atoms of acceptor solvent water molecules are indicated by the w subscript. The hydrogen bonds with water solvent molecules as donors are omitted. b Hydrogen atoms not found. Symmetry codes: 1: 0 = x, -y, z þ 1/2; 4: 0 = 1 - x, 1 - y, 1 - z; 5: 0 = 1 - x, y - 1/2, 3/2 - z; 6: 0 = -x, 2 - y, -z.

Figure 1. Top: View of complex 1. Displacement ellipsoids are drawn at the 30% probability level. Counterions, solvent molecules, and carbon-bound hydrogen atoms are omitted. Only one position of the disordered ligands is represented for each uranium atom. Symmetry code: 0 = 2 - x, y, 3/2 - z. Bottom: Space filling representation of the perrhenate ion encapsulated in CB6. Hydrogen atoms are omitted. The CB6 oxygen atoms are in red, and those of the anion are in orange. The binary axis is vertical.

monodentate CB6 complexes.4 The five-coordinate uranyl ion is also bound to one perrhenate ion located trans with respect to the macrocycle and half a perrhenate ion, which occupies the same coordination site as an aqua ligand, with both having been given occupancy parameters of 0.5. The U-O10 bond length of 2.353(7) A˚ is in agreement with the average value of 2.37(3) A˚ for the similar structures reported in the Cambridge Structural Database (CSD, Version 5.30),17 but the larger U-O14 bond length may be affected by the disorder effects and the bad resolution of the anion (see the Experimental Section). The last coordination site is occupied by an aqua ligand, and the resulting coordination polyhedron is the usual pentagonal bipyramid. Another, uncoordinated perrhenate ion is encapsulated in the macrocycle cavity, and an additional HReO4 moiety is located in the intermolecular space. Such encapsulation of an otherwise free ReO4- ion has only been observed once, in the complex [Yb(H2O)8](ReO4)3 3 CB6 3 6H2O.8 As can be seen in Figure 1, the CB6 moiety in 1 is much distorted, with O 3 3 3 O distances between adjacent

oxygen atoms in one portal in the range 3.228(11)-3.841(11) A˚, apart from that between the two coordinated atoms O3 and O5, which is very short, at 2.811(10) A˚. The distances between oxygen atoms diametrically opposed in the portal reveal a pronounced ellipsoidal distortion, with O7 3 3 3 O40 [5.703(13) A˚], much shorter than O3 3 3 3 O80 [7.421(10) A˚] and O5 3 3 3 O60 [7.334(10) A˚]. Such a distortion was also observed in some lanthanide complexes with a coordinated and included perrhenate ion and also in the case of encapsulation of an uncoordinated perrhenate, but a more circular portal shape could also be observed, depending on the coordination mode of CB6.8 Two perrhenate oxygen atoms point toward each portal aperture in 1; the only short contacts lower than 3 A˚ between the host and its guest involve carbon atoms of carbonyl groups [O19 3 3 3 C1 2.942 A˚, O20 3 3 3 C16 2.882 A˚], whereas the contacts with oxygen and nitrogen atoms are longer [for example, O19 3 3 3 O3 3.109 A˚ and O20 3 3 3 O8 3.192 A˚]. A similar perrhenate position, with two atoms pointing toward each portal and the shortest contacts involving carbonyl carbon atoms, was also adopted in the ytterbium complex cited above, which suggests that this is the preferred situation in the case of an uncoordinated perrhenate ion. In this case, as noted previously,8 ReO4- is located nearer to the less electron-rich part of the CB6 cavity, thus suggesting the presence of ion-dipole interactions. The packing brings the dinuclear complexes side-by-side, with the usual match between bumps and hollows, and there are no noticeable intermolecular interactions apart from the hydrogen bonds involving the water molecules (Table 3). The complex [UO2(CB7)(NO3)(H2O)2](ReO4) 3 5H2O (2) will be described very succinctly, since it presents many analogies with [UO2(CB7)(NO3)(H2O)2](ReO4) 3 10H2O (7), previously reported and obtained under identical conditions.6 The uranyl ion is bound to two CB7 molecules in monodentate fashion, with an average U-O(carbonyl) bond length of 2.399(19) A˚ similar to that in 7, but instead of occupying adjacent coordination sites in the uranyl equatorial plane, the CB7 molecules in 2 are separated by an aqua ligand (O6) involved in a hydrogen bond with a carbonyl group (Figure 2). Another aqua ligand and a nitrate ion are present, and the ligands are thus overall identical in both cases but, whereas the

720


Thuery and Masci

Figure 2. Top: View of complex 2. Displacement ellipsoids are drawn at the 50% probability level. Counterions, solvent molecules, and hydrogen atoms are omitted. The hydrogen bond is shown as a dashed line. Symmetry codes: 0 = 1 - x, y þ 1/2, 2 - z; 00 = 1 - x, y - 1/2, 2 - z. Bottom: View of the packing down the c axis. Solvent molecules and hydrogen atoms are omitted. Uranium atoms are in yellow, and rhenium atoms are in green.

nitrate ion in 7 displays a very unusual coordination mode (bidentate and parallel to the uranyl axis), it assumes the much more usual monodentate coordination mode in 2. In both compounds, a one-dimensional zigzag polymer is formed. The average planes of the portals containing O8 and O90 make dihedral angles of 86.63(19) and 82.12(19), respectively, with the uranyl mean equatorial plane, and of 78.39(7) with one another. The latter angle is associated with the presence of CH 3 3 3 O interactions (shortest H 3 3 3 O distance 2.26 A˚) between the CB7 molecules bound to the same uranyl unit; such interactions are very frequently encountered in cucurbituril structures.2a,j,4-6,8,18 Although perrhenate inclusion in

CB7 has been observed in the compound {[Yb(CB7)2(H2O)4][Yb(ReO4)(NO3)(H2O)5]2}[Yb(CB7)(ReO4)(H2O)3][Yb(H2O)8](ReO4)10 3 CB7 3 21H2O,8 it is absent in the two uranyl complexes obtained under similar conditions. This suggests that it is less favorable than in the case of CB6, for which it is a general phenomenon, probably owing to the better size match, with CB7 being slightly too large for this cation. It is also interesting to note that complexes 2 and 7, which are overall analogous but differ slightly in the details of geometry and coordination mode, resulted from nearly identical experimental procedures, which points to the versatility of these large systems, as previously exemplified in the case of lanthanide ions.2,8

Article

Figure 3. Top: View of complex 3. Displacement ellipsoids are drawn at the 30% probability level. Carbon-bound hydrogen atoms are omitted. Hydrogen bonds are shown as dashed lines. Symmetry codes: 0 = 1 - x, y, -z; 00 = 1/2 - x, 1/2 - y, -z; 000 = 1/2 þ x, 1/2 - y, z; 0000 = 3/2 - x, 1/2 - y, -z; # = x, -y, z. Middle: View of the uranyl phosphate chain. Bottom: View of the packing down the a axis. Solvent molecules and hydrogen atoms are omitted.

Complex 3, [UO2(H2PO4)2(H2O)]2 3 CB6 3 H3PO4 3 6H2O, was obtained in the presence of orthophosphoric acid, and it comprises two coordinated dihydrogen phosphate anions H2PO4- as well as a free H3PO4 molecule (Figure 3). While ReO4- anions, although coordinated to uranyl, do not give polymers in the presence of CB6 under the conditions used (although they can give dimers15c,d or polymers15d in other systems), H2PO4- gives a one-dimensional polymer, whereas SO42- has been shown to be able to give either dimeric or onedimensional subunits.4 In contrast with the latter cases in which the uranyl sulfate moieties were bound to CB molecules through uranium-carbonyl bonds, the uranyl dihydrogen phosphate chain in 3 is dissociated from CB6. The latter can be viewed as a templating species, with 3 being thus part of the


721

much studied family of organically templated uranyl phosphates,19 phosphites,20 or phosphonates.21 The uranyl ion is bound to two bridging H2PO4- groups, with an average U-O bond length of 2.347(17) A˚, in agreement with the average value of 2.32(3) A˚ for the uranyl-dihydrogen phosphate bonds reported in the CSD. The presence of dihydrogen phosphate in 3 is unsurprising, since this is the most abundant species resulting from orthophosphoric acid dissociation in a large concentration range. An aqua ligand completes the uranium coordination sphere, which is pentagonal bipyramidal; both the uranium atom and the aqua oxygen atom are located on a binary axis. The hydrogen atoms of the anion have been found during the structure refinement, and it appears that, as expected, the P-O bond lengths are larger for the protonated [average 1.569(2) A˚] than for the deprotonated oxygen atoms [1.476(9) A˚]. [UO2(H2PO4)2(H2O)]¥ neutral chains parallel to the a axis are formed, with two bridging H2PO4- ions separating the metal cations related to one another by inversion centers, and the aqua ligands located alternately on opposite sides of the chain. Analogous chains are present in the complexes [UO2(H2PO4)2(H2O)]2 3 18crown-6 3 5H2O and [UO2(H2PO4)2(H2O)] 3 18-crown-6 3 3H2O, in which the crown ether behaves as a templating agent.19b The OH groups of the anion in 3 form hydrogen bonds with the uncoordinated orthophosphoric acid molecule (in which the protons have not been found) and a solvent water molecule. Although its protons were not found, the short contacts around O6 indicate that the aqua ligand is involved in two hydrogen bonds with O7 and its symmetry equivalent through the binary axis, with O6 3 3 3 O7=2.715(12) A˚ and O7 3 3 3 O6 3 3 3 O70 =112.5(6). The proton of O7 in its turn is likely involved in a hydrogen bond with the water molecule O13 [O7 3 3 3 O13 = 2.880(13) A˚]; O8 is at hydrogen bonding distances from one of its images by symmetry [2.75(4) A˚] and a CB6 carbonyl oxygen atom [2.875(15) A˚] while O9 is not involved in hydrogen bonding and may be assumed to be the unprotonated oxygen atom. An extended hydrogen bonded framework associating the uranyl chains and the CB6 molecules via the solvent and perrhenic acid molecules is thus formed. The packing of the chains is different from that in the compounds including 18-crown-6. In the latter compounds, this packing forms a pseudohexagonal array when viewed down the chain axis, while it defines a square array in 3, with the CB6 molecules arranged in columns parallel to the chains and centered between four chains. In order to synthesize uranyl-organic polymers with CB6 including bridging anions, such as those obtained with sulfate but not with perrhenate and phosphate ions, it seemed interesting to use polytopic carboxylic acids as additional reagents. Among those which were tried, three yielded a crystalline material suitable for structure determination: oxalic acid (generated in situ from tartaric acid), pyrazinetetracarboxylic acid (H4PZTC), and citric acid (H4cit). Oxalate formation from tartaric22 and other carboxylic acids23 under hydrothermal conditions has previously been observed. The complex [(UO2)4(C2O4)3(NO3)2(H2O)6] 3 CB6 3 6H2O (4) is however not polymeric, and as in complex 3, there is no uranium-CB6 bond. A centrosymmetric neutral tetranuclear uranyl oxalate species is formed instead, and it crystallizes together with CB6 (Figure 4). There are two independent uranium atoms in the asymmetric unit. U1 is bound to two bridging, bis-bidentate oxalate and one chelating nitrate ligands while U2 is bound to one bridging oxalate and three terminal aqua ligands.

722


Thuery and Masci

Figure 4. Top: View of complex 4. Displacement ellipsoids are drawn at the 50% probability level. Solvent molecules and carbon-bound hydrogen atoms are omitted. The hydrogen bond is shown as a dashed line. Symmetry codes: 0 = -x, 2 - y, 2 - z; 00 = 1 - x, 1 - y, 2 - z. Bottom: View of the two-dimensional hydrogen bonded assembly. Solvent molecules and hydrogen atoms are omitted. Hydrogen bonds are shown as dotted lines.

The coordination environment geometries are thus hexagonal and pentagonal bipyramidal for U1 and U2, respectively. The average U-O(oxalate) bond lengths, 2.478(16) and 2.445(12) A˚ for U1 and U2, respectively, as well as the average U1O(nitrate) bond length of 2.511(16) A˚ and U2-O(aqua) bond length of 2.372(1) A˚, are unexceptional. No other example of the [(UO2)4(C2O4)3(NO3)2(H2O)6] moiety is present in the CSD, and it is likely the first instance of a tetranuclear uranyl oxalate complex, which may be ascribed to the

structure-directing effect of the uncomplexed CB6 molecules. The uranyl oxalate complexes reported in the CSD are mononuclear, dinuclear, or polymeric; in particular, some dinuclear oxalate nitrate species are known.24 Each of the three aqua ligands in 4 is involved in two hydrogen bonds, one with a CB6 carbonyl oxygen atom, and the other with a solvent water molecule (Table 3). Since O14 on the one hand and O15 and O16 on the other are bound to two different CB6 molecules, each tetranuclear unit is bound to four CB6 molecules and a

Article


723

Figure 5. Top: View of complex 5. Displacement ellipsoids are drawn at the 50% probability level. Solvent molecules and carbon-bound hydrogen atoms are omitted. Hydrogen bonds are shown as dashed lines. Symmetry codes: 0 = 1 - x, 2 - y, 1 - z; 00 = 2 - x, 2 - y, 2 - z. Bottom: View of the packing of the chains. Solvent molecules and hydrogen atoms are omitted.

two-dimensional hydrogen bonded network parallel to (1 1 0) is formed. Only weak hydrogen bonds between solvent water molecules and uranyl oxo atoms (O 3 3 3 O distance 2.99 A˚) span the interlayer space. As expected, the packing of the layers brings the bumps of one layer in contact with the hollows of its neighbors. The ligand PZTC4-, present in the complex [(UO2)2(PZTC)(CB6)(H2O)2] 3 12H2O (5), has already been investigated as an assembler in uranyl-organic frameworks.25 As in the complexes previously reported, the uranyl ion in 5 is O,N,O-chelated by PZTC4-, with the latter being centrosymmetric and bridging two cations (Figure 5). The U-N and average U-O bond lengths, 2.576(4) and 2.342(8) A˚, respectively, are in agreement with those for five-coordinate uranyl ions bound in a similar fashion to pyridine-2,6-dicarboxylate or pyrazine-2,6-dicarboxylate, 2.54(2) and 2.38(2) A˚ (uranyl is chelated by two ligands in its complexes with PZTC and hence six-coordinate).25 The uranium atom in 5 is also bound to a carbonyl group, with an unexceptional U-O bond

length of 2.357(4) A˚, and to an aqua ligand, which gives a pentagonal bipyramidal geometry. The CB6 molecule is located around an inversion center, and it is thus bridging two uranyl ions. Neutral chains parallel to the [101] direction, with alternate PZTC4- and CB6 ligands, are thus formed. The aqua ligand is involved in hydrogen bonds with two solvent water molecules, one of them located at the CB6 portal and hydrogen bonded to two carbonyl groups. The other water molecules ensure the formation of a three-dimensional hydrogen bonded network. Compound 5 is the first example, in this family of uranyl complexes, of a very regular structure including two different organic ligands, with one of them being the CB6 molecule. Albeit the structure is one-dimensional only, each ligand retains uncomplexed donor atoms and higher dimensionality frameworks could be expected to be attainable, possibly by using additional cations, since it has previously been shown that H4-xPZTCx- (x=2 or 4) can use all its donor atoms in coordination or be bound to as many as seven metal atoms.25

724


Thuery and Masci

three-dimensional framework in [(UO2)3(Hcit)2(H2O)3] 3 2H2O,26a the citrate ligand generally gives dinuclear, dimeric units, in which each uranium atom is bound to two carboxylates (the R and one of the β groups) and the alkoxide donors of each ligand.26b-d Such a unit is present in 6, formed by the atom U2 and its image by inversion and two completely deprotonated citrate moieties (Figure 6). The average U2O(alkoxide) bond length of 2.389(18) A˚ matches those in the former complexes [2.378(16) A˚], but the average U2O(carboxylate) bond length of 2.419(7) A˚ appears slightly (but not quite significantly) larger than the previous mean value of 2.355(18) A˚, which may be due to the bridging nature of these carboxylate groups in 6. Indeed, the two groups bound to U2 are also bound either to U1 or to its image by symmetry, with U1 also being linked to one carbonyl group of CB6; the U1-O(carbonyl) and average U1-O(carboxylate) bond lengths of 2.387(6) and 2.41(2) A˚ are unexceptional. Lastly, the third carboxylate group of citrate, directed away from the dimer mean plane, chelates the six-coordinate uranium atom U3, which is located on an inversion center, with an average U3-O(carboxylate) bond length of 2.458(4) A˚. The uranium coordination sphere is completed by one (U1 and U2) or two (U3) aqua ligands and a monodentate nitrate ion (U1) to give pentagonal (U1 and U2) or hexagonal (U3) bipyramidal environment geometries. As can be seen in Figure 6, this quite intricate assembly also displays intramolecular hydrogen bonds involving the aqua ligands of U1 (O16) and U3 (O18) and the CB6 molecule, while the aqua ligand of U2 (O17) is only hydrogen bonded to solvent water molecules. Starting from the asymmetric unit, the structure extends in five directions, through the three centrosymmetric units (citrate dimer, U3, and CB6) and the atoms U1 and O10; each citrate moiety is thus bound to five metal ions. A compact three-dimensional framework is formed, in which no significant channel or void exists. In contrast to PZTC in 5, the citrate ligand displays here an outstanding assembling potential, with the usual uranyl citrate dimer further connecting six cations. In fact, as shown in Figure 6, uranyl citrate alone builds a three-dimensional subunit defining cagelike spaces in which the CB6 molecules are held by bonding to the sidedefining U1 atoms. Notwithstanding the different dimensionalities of the subunits, this situation is reminiscent of that in the complexes [K2(CB5)(H2O)][(UO2)2(HCOO)(OH)4]2 3 6H2O and [Cs2(CB5)(H2O)2][(UO2)2(HCOO)(OH)4]2 3 3H2O, in which the CB5 capsules, capped by Kþ or Csþ at both portals, are held in the spaces between uranyl formate twodimensional layers by coordination bonds.5

Figure 6. Top: View of complex 6. Displacement ellipsoids are drawn at the 40% probability level. Solvent molecules and carbonbound hydrogen atoms are omitted. Hydrogen bonds are shown as dashed lines. Symmetry codes: 0 = x, 3/2 - y, z þ 1/2; 00 = 1 - x, 2 - y, -z; 000 = x, 3/2 - y, z - 1/2; # = -x, 2 - y, -z; $ = -x, 2 - y, 1 - z. Middle: View of the three-dimensional uranyl citrate subunit down the a axis. Bottom: View of the three-dimensional framework down the a axis. Atom U3 projects at the center of the citrate dimer. Solvent molecules and hydrogen atoms are omitted.

A polymer including both CB6 and a polycarboxylate as ligands is also present in compound [(UO2)5(cit)2(CB6)(NO3)2(H2O)6] 3 7H2O (6). The first crystal structures of the complexes formed by uranyl ions with citric acid were reported only recently.26 Apart from being able to form a

Conclusions This work was aimed at investigating the complexes formed between uranyl ions and cucurbiturils in the presence of additional ligands, with these being either tetrahedral oxoanions or polycarboxylates. Among the former, the perrhenate ion can behave either as a complexing species in complex 1 or as a simple counterion in 2, but in both cases, as in previous studies with lanthanide ions,8 it appears unable to promote the formation of a coordination polymer, being bound to one uranyl ion at most. The perrhenate encapsulation of an otherwise free perrhenate ion is once more observed in complex 1, with another example having been given in the lanthanide ion complexes family, while in all other cases the included perrhenate is bound to one or two lanthanide cations. As was the case with sulfate ions in a previously reported structure,

Article


dihydrogen phosphate ions give a one-dimensional polymer with uranyl ions in compound 3; the CB6 molecules are not coordinated to uranyl in this case but simply play the role of structure-directing agent; as such, their main characteristics are their bulkiness and their tendency to form hydrogen bonds. Up to now, apart from sulfate ions, no tetrahedral oxoanion gives a uranyl complex framework including cucurbiturils as ligands. Turning our attention to polycarboxylates gives more interesting results. In the case of oxalate, generated in situ from tartaric acid, the unprecedented tetranuclear, neutral uranyl oxalate unit [(UO2)4(C2O4)3(NO3)2(H2O)6] is formed, likely as a result of the structure-directing effect of CB6, which is hydrogen bonded to the complex. Genuine mixed-ligand uranyl-organic frameworks27 are obtained with PZTC4- or cit4-. Such mixedligand metal-organic28 and uranyl-organic29 frameworks have been much investigated in the case of the N-donor bipyridyl molecules associated with carboxylate ligands, but all ligands are O-donors in the present cases. The ligands PZTC4- and CB6 alternate along a one-dimensional polymer in complex 5, while compound 6 comprises an intricate threedimensional framework including citrate and CB6 ligands, with the uranyl citrate part itself building a three-dimensional subunit in the free spaces of which the CB6 molecules are nestled. These last two examples demonstrate the interest of cucurbiturils as auxiliary ligands in the synthesis of mixed-ligand uranyl-organic frameworks, with their large size and rigidity endowing them with quite unique geometric properties. Supporting Information Available: Tables of crystal data, atomic positions and displacement parameters, anisotropic displacement parameters, and bond lengths and bond angles in CIF format. This information is available free of charge via the Internet at http:// pubs.acs.org.

References (1) (a) Freeman, W. A.; Mock, W. L.; Shih, N. Y. J. Am. Chem. Soc. 1981, 103, 7367. (b) Lee, J. W.; Samal, S.; Selvapalam, N.; Kim, H. J.; Kim, K. Acc. Chem. Res. 2003, 36, 621. (c) Kim, K.; Selvapalam, N.; Oh, D. H. J. Inclusion Phenom. 2004, 50, 31. (d) Lagona, J.; Mukhopadhyay, P.; Chakrabarti, S.; Isaacs, L. Angew. Chem., Int. Ed. 2005, 44, 4844. (e) Isaacs, L. Chem. Commun. 2009, 619. (2) (a) Samsonenko, D. G.; Lipkowski, J.; Gerasko, O. A.; Virovets, A. V.; Sokolov, M. N.; Fedin, V. P.; Platas, J. G.; Hernandez-Molina, R.; Mederos, A. Eur. J. Inorg. Chem. 2002, 2380. (b) Samsonenko, D. G.; Gerasko, O. A.; Lipkowski, J.; Virovets, A. V.; Fedin, V. P. Russ. Chem. Bull. 2002, 51, 1915. (c) Samsonenko, D. G.; Sokolov, M. N.; Gerasko, O. A.; Virovets, A. V.; Lipkowski, J.; Fenske, D.; Fedin, V. P. Russ. Chem. Bull. 2003, 52, 2132. (d) Gerasko, O. A.; Sokolov, M. N.; Fedin, V. P. Pure Appl. Chem. 2004, 76, 1633. (e) Tripolskaya, A. A.; Mainicheva, E. A.; Mitkina, T. V.; Gerasko, O. A.; Naumov, D. Y.; Fedin, V. P. Russ. J. Coord. Chem. 2005, 31, 768. (f) Mainicheva, E. A.; Tripolskaya, A. A.; Gerasko, O. A.; Naumov, D. Y.; Fedin, V. P. Russ. Chem. Bull. 2006, 55, 1566. (g) Mainicheva, E. A.; Gerasko, O. A.; Sheludyakova, L. A.; Naumov, D. Y.; Karsanova, I. I.; Amirov, R. R.; Fedin, V. P. Russ. Chem. Bull. 2006, 55, 1956. (h) Tripolskaya, A. A.; Gerasko, O. A.; Naumov, D. Y.; Fedin, V. P. J. Struct. Chem. 2007, 48, 949. (i) Tripolskaya, A. A.; Mainicheva, E. A.; Gerasko, O. A.; Naumov, D. Y.; Fedin, V. P. J. Struct. Chem. 2007, 48, 547. (j) Gerasko, O. A.; Mainicheva, E. A.; Naumova, M. I.; Yurjeva, O. P.; Alberola, A.; Vicent, C.; Llusar, R.; Fedin, V. P. Eur. J. Inorg. Chem. 2008, 416. (k) Gerasko, O. A.; Mainicheva, E. A.; Naumova, M. I.; Neumaier, M.; Kappes, M. M.; Lebedkin, S.; Fenske, D.; Fedin, V. P. Inorg. Chem. 2008, 47, 8869. (3) Gerasko, O. A.; Samsonenko, D. G.; Sharonova, A. A.; Virovets, A. V.; Lipkowski, J.; Fedin, V. P. Russ. Chem. Bull. 2002, 51, 346. (4) Thuery, P. Cryst. Growth Des. 2008, 8, 4132. (5) Thuery, P. Cryst. Growth Des. 2009, 9, 1208. (6) Thuery, P. CrystEngComm 2009, 11, 1150. (7) Thuery, P. Inorg. Chem. 2009, 48, 825.

725

(8) Thuery, P. Inorg. Chem. 2009, 48, 4497. (9) Vishweshwar, P.; Babu, N. J.; Nangia, A.; Mason, S. A.; Pushmann, H.; Mondal, R.; Howard, J. A. K. J. Phys. Chem. A 2004, 108, 9406. (10) Hooft, R. W. W. COLLECT; Nonius BV: Delft, The Netherlands, 1998. (11) Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307. (12) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112. (13) Ozawa, T. C.; Kang, S. J. J. Appl. Crystallogr. 2004, 37, 679. (14) Thuery, P. CrystEngComm 2008, 10, 1126. (15) (a) John, G. H.; May, I.; Sarsfield, M. J.; Steele, H. M.; Collison, D.; Helliwell, M.; McKinney, J. D. Dalton Trans. 2004, 734. (b) Sutton, A. D.; John, G. H.; Sarsfield, M. J.; Renshaw, J. C.; May, I.; Martin, L. R.; Selvage, A. J.; Collison, D.; Helliwell, M. Inorg. Chem. 2004, 43, 5480. (c) John, G. H.; May, I.; Sarsfield, M. J.; Collison, D.; Helliwell, M. Dalton Trans. 2007, 1603. (d) Karimova, O. V.; Burns, P. C. Inorg. Chem. 2007, 46, 10108. (16) (a) Oliveira, M. A.; Miranda, J. M.; Castellano, E. E.; Scoralick, E.; Zinner, L. B.; Vicentini, G. Lanthanide Actinide Res. 1986, 1, 205. (b) Miranda, J. M.; Oliveira, M. A.; Castellano, E. E.; Scoralick, E.; Zinner, L. B.; Vicentini, G. Inorg. Chim. Acta 1987, 139, 131. (c) Fedosseev, A. M.; Grigoriev, M. S.; Charushnikova, I. A.; Budantseva, N. A.; Starikova, Z. A.; Moisy, P. Polyhedron 2008, 27, 2007. (17) Allen, F. H. Acta Crystallogr., Sect. B 2002, 58, 380. (18) Hwang, I.; Jeon, W. S.; Kim, H. J.; Kim, D.; Kim, H.; Selvapalam, N.; Fujita, N.; Shinkai, S.; Kim, K. Angew. Chem., Int. Ed. 2007, 46, 210. (19) (a) Francis, R. J.; Drewitt, M. J.; Halasyamani, P. S.; Ranganathachar, C.; O’Hare, D.; Clegg, W.; Teat, S. J. Chem. Commun. 1998, 279. (b) Danis, J. A.; Hawkins, H. T.; Scott, B. L.; Runde, W. H.; Scheetz, B. E.; Eichhorn, B. W. Polyhedron 2000, 19, 1551. (c) Danis, J. A.; Runde, W. H.; Scott, B.; Fettinger, J.; Eichhorn, B. Chem. Commun. 2001, 2378. (d) Doran, M. B.; Stuart, C. L.; Norquist, A. J.; O'Hare, D. Chem. Mater. 2004, 16, 565. (e) Locock, A. J.; Burns, P. C. J. Solid State Chem. 2004, 177, 2675. (f) Ok, K. M.; Doran, M. B.; O'Hare, D. Dalton Trans. 2007, 3325. (g) Yu, Y.; Zhan, W.; Albrecht-Schmitt, T. E. Inorg. Chem. 2007, 46, 10214. (20) Doran, M.; Walker, S. M.; O’Hare, D. Chem. Commun. 2001, 1988. (21) Knope, K. E.; Cahill, C. L. Inorg. Chem. 2009, 48, 6845. (22) Thuery, P. Polyhedron 2007, 26, 101. (23) (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) Frisch, M.; Cahill, C. L. J. Solid State Chem. 2007, 180, 2597. (e) Ziegelgruber, K. L.; Knope, K. E.; Frisch, M.; Cahill, C. L. J. Solid State Chem. 2008, 181, 373. (24) (a) Bradley, A. E.; Hatter, J. E.; Nieuwenhuyzen, M.; Pitner, W. R.; Seddon, K. R.; Thied, R. C. Inorg. Chem. 2002, 41, 1692. (b) Bradley, A. E.; Hardacre, C.; Nieuwenhuyzen, M.; Pitner, W. R.; Sanders, D.; Seddon, K. R.; Thied, R. C. Inorg. Chem. 2004, 43, 2503. (25) Masci, B.; Thuery, P. Cryst. Growth Des. 2008, 8, 1689. (26) (a) Thuery, P. Chem. Commun. 2006, 853. (b) Thuery, P. Inorg. Chem. 2007, 46, 2307. (c) Thuery, P. CrystEngComm 2007, 9, 358. (d) Thuery, P. CrystEngComm 2008, 10, 79. (27) For other examples of uranyl-organic frameworks, see: (a) Kim, J. Y.; Norquist, A. J.; O’Hare, D. Dalton Trans. 2003, 2813. (b) Borkowski, L. A.; Cahill, C. L. Inorg. Chem. 2003, 42, 7041. (c) Yu, Z. T.; Li, G. H.; Jiang, Y. S.; Xu, J. J.; Chen, J. S. Dalton Trans. 2003, 4219. (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) Yu, Z. T.; Liao, Z. L.; Jiang, Y. S.; Li, G. H.; Li, G. D.; Chen, J. S. Chem. Commun. 2004, 1814. (f) Yu, Z. T.; Liao, Z. L.; Jiang, Y. S.; Li, G. H.; Chen, J. S. Chem.;Eur. J. 2005, 11, 2642. (g) Jiang, Y. S.; Li, G. H.; Tian, Y.; Liao, Z. L.; Chen, J. S. Inorg. Chem. Commun. 2006, 9, 595. (h) Thuery, P. Eur. J. Inorg. Chem. 2006, 3646. (i) Knope, K. E.; Cahill, C. L. Inorg. Chem. 2007, 46, 6607. (j) Dean, N. E.; Hancock, R. D.; Cahill, C. L.; Frisch, M. Inorg. Chem. 2008, 47, 2000. (k) Thuery, P. Inorg. Chem. Commun. 2008, 11, 616. (l) Thuery, P.; Masci, B. Cryst. Growth Des. 2008, 9, 3430. (m) Liao, Z. L.; Li, G. D.; Bi, M. H.; Chen, J. S. Inorg. Chem. 2008, 47, 4844. (n) Knope, K. E.; Cahill, C. L. Inorg. Chem. 2008, 47, 7660. (o) Thuery, P. CrystEngComm 2009, 11, 1081. (p) Thuery, P. CrystEngComm 2009, 11, 2319. (28) Ye, B. H.; Tong, M. L.; Chen, X. M. Coord. Chem. Rev. 2005, 249, 545. (29) (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, pp 409-442.

Uranyl Ion Complexation by Cucurbiturils in the Presence of Perrhenic

Recommend Documents