Uranyl Ion Complexes with Ammoniobenzoates as Assemblers for

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Uranyl Ion Complexes with Ammoniobenzoates as Assemblers for Cucurbit[6]uril Molecules Pierre Thuery* CEA, IRAMIS, UMR 3299 CEA/CNRS, SIS2M, Laboratoire de Chimie de Coordination des Elements f, Bât. 125, 91191 Gif-sur-Yvette, France

bS Supporting Information ABSTRACT: The crystal structures of the complexes formed under hydrothermal conditions by uranyl ions with 4-aminobenzoic (HL1), 4-amino-3-methylbenzoic (HL2), 4(aminomethyl)benzoic (HL3), and 3-amino-5-hydroxybenzoic (HL4) acids, in the presence of cucurbit[6]uril (CB6), have been determined. These ligands have been chosen because, in their zwitterionic form, they display both a metal-complexing carboxylate group and an ammonium group able to associate with CB6 through ion-dipole and hydrogen bonding interactions. The complexes [H2NMe2]2[(UO2)2(L1)2O(OH)(H2O)]2 3 CB6 3 15H2O (1) and [H2NMe2]2[(UO2)2(L2)2O(OH)(H2O)]2 3 CB6 3 17H2O (2) were obtained in the presence of dimethylformamide, which gives dimethylammonium ions in situ. The latter are held at the CB6 portals, while the tetranuclear uranyl complex with the aminobenzoate anions is not bound to CB6. The neutral, ammonium-containing form of the ligand is present in [UO2(HL3)(OH)(HCOO)(H2O)]2 3 2CB6 3 2DMF 3 14H2O (3), in which the di(μ2-hydroxo)-bridged, dinuclear uranyl complex displays two diverging, monodentate HL3 ligands. The latter are associated with two CB6 molecules to give a dumbbell-shaped supramolecular assembly. Three CB6 molecules are assembled around a tetranuclear uranyl complex in [(UO2)4(HL3)2(L3)O2(OH)2(H2O)4] 3 2CB6 3 0.5CB8 3 HL3 3 NO3 3 20H2O (4), with two of them being bridging and giving rise to a one-dimensional, linear supramolecular architecture. Finally, the 3-amino substituted ligand HL4 gives the highly symmetric complex [UO2(HL4)(L4)2] 3 3CB6 3 16H2O (5), in which the uranyl ion is chelated by three carboxylate groups. Three CB6 molecules are assembled around the planar complex to give a triangular, discrete species. In compounds 3 5, the usual packing of CB6 molecules into columns or layers is not retained as it is frequently in the presence of uranyl complexes. This is due to the CB6-assembling role of the heterodifunctional ligands, which hold the CB6 molecules at the periphery of mono-, di-, or tetranuclear uranyl complexes of quite usual, planar geometry.

’ INTRODUCTION The affinity of cucurbiturils1 for ammonium ions, originating in charge dipole and hydrogen bonding interactions, is central to the use of these macrocycles in the design of supramolecular systems. The host guest complexes formed by cucurbit[6]uril (CB6, Scheme 1) with alkyl- and aryl-substituted ammonium cations, for which hydrophobic effects allow for the inclusion of the substituents, were investigated early.2 CB6 complexation of diaminoalkanes2a,c,3 proved to be particularly important since it paved the way for the synthesis of polyrotaxanes and molecular necklaces involving metal ion coordination by functional groups located at both ends of the included species.4 Molecules incorporating a single ammonium group may also be of interest for the building of metal-containing supramolecular assemblies since, if they are properly functionalized, they can be used as linkers between the metal ion and the CB6 moiety. Recently, iminodiacetic acid, in its zwitterionic form, was shown to be able to complex a lanthanide ion through its carboxylate group while being attached to CB6 by its ammonium function, with the unusual consequence of the uncomplexed carboxylic acid group being included in the CB6 cavity.5 α-Amino-acids in their zwitterionic form are also heterofunctional molecules suitable as linkers between metal ions and CB6, as shown in the chiral, columnar r 2011 American Chemical Society

Scheme 1. Cucurbit[6]uril

one-dimensional assemblies obtained with lanthanide ions, in which the latter are bound to both carboxylate and CB6 moieties.6 It seemed interesting to extend these studies to the uranyl ion, which is Received: October 24, 2011 Revised: November 14, 2011 Published: December 16, 2011 499

dx.doi.org/10.1021/cg2014072 | Cryst. Growth Des. 2012, 12, 499–507

Crystal Growth & Design

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the most accessible form of an actinide cation and is readily complexed by cucurbiturils to give a large array of architectures of varying dimensionality.7 However, attempts at obtaining similar complexes with this ion and iminodiacetic acid or α-amino-acids were unsuccessful, which led to the search for other suitable aminocarboxylic acids. The family of aminobenzoic acids appeared of interest for the variations it provides on the relative positions of the functional groups, and the possible presence of additional substituents. Uranyl ion complexes with 4-aminobenzoic (HL1),

4-amino-3-methylbenzoic (HL2), 4-(aminomethyl)benzoic (HL3), and 3-amino-5-hydroxybenzoic (HL4) acids (Scheme 2) could be crystallized in the presence of CB6 molecules, and the structures of the compounds obtained, which display novel features among the family of uranyl cucurbituril compounds, 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. Caution is also needed when working with glass vessels under pressure. UO2(NO3)2 3 6H2O was purchased from Prolabo (depleted uranium, R. P. Normapur, 99%), CsNO3 (99.9%) from Acros, 4-amino-3methylbenzoic (98%) and 4-(aminomethyl)benzoic (97%) acids from Aldrich, and 4-aminobenzoic acid (99%), 3-amino-5-hydroxybenzoic acid hydrochloride (97%), and cucurbit[6]uril pentahydrate (g95%) from Fluka. Elemental analyses were performed by MEDAC Ltd., UK. [H2NMe2]2[(UO2)2(L1)2O(OH)(H2O)]2 3 CB6 3 15H2O (1). CB6 3 5H2O (11 mg, 0.01 mmol), a 10-fold excess of UO2(NO3)2 3 6H2O (50 mg, 0.10 mmol) and HL1 (14 mg, 0.10 mmol), DMF (0.5 mL), and demineralized water (1.2 mL) were placed in a 15 mL tightly closed glass vessel and heated at 180 °C under autogenous pressure. Light yellow crystals of complex 1 appeared within 24 h (17 mg, 55% yield on the basis of CB6). Anal. Calcd for C68H112N30O49U4: C, 26.47; H, 3.66; N, 13.62. Found: C, 26.00; H, 3.19; N, 13.58%. [H2NMe2]2[(UO2)2(L2)2O(OH)(H2O)]2 3 CB6 3 17H2O (2). CB6 3 5H2O (11 mg, 0.01 mmol), a 10-fold excess of UO2(NO3)2 3 6H2O (50 mg, 0.10 mmol) and HL2 (15 mg, 0.10 mmol), DMF (0.5 mL), and demineralized water (1.2 mL) were placed in a 15 mL tightly closed glass vessel and heated at 180 °C under autogenous pressure. Light yellow crystals of complex 2 appeared within one week.

Scheme 2. The Aminobenzoic Acids under Study

Table 1. Crystal Data and Structure Refinement Details 1

2

3

4

5

chemical formula

C68H112N30O49U4

C72H124N30O51U4

C96H140N52O56U2

C128H181N69O79U4

C129H159N75O63U

M (g mol 1)

3086.00

3178.13

3394.66

4902.54

4006.34

cryst syst

monoclinic

monoclinic

monoclinic

monoclinic

hexagonal

space group a (Å)

P21/n 12.2719(2)

P21/n 12.4840(6)

P21/n 13.1650(4)

P21/c 17.8308(8)

P63/m 24.2936(6)

b (Å)

23.9584(4)

23.8021(12)

16.6185(5)

29.1315(10)

24.2936(6)

c (Å)

16.5871(3)

17.3035(7)

28.8324(10)

36.6998(18)

15.6891(3)

α (deg)

90

90

90

90

90

β (deg)

90.4637(6)

92.533(3)

98.013(2)

98.238(3)

90

γ (deg)

90

90

90

90

120

V (Å3)

4876.70(14)

5136.6(4)

6246.4(3)

18866.6(14)

8018.9(5)

Z Dcalcd (g cm 3)

2 2.102

2 2.055

2 1.805

4 1.726

2 1.659

μ(Mo Kα) (mm 1)

6.735

6.399

2.710

3.534

1.132

F(000)

2980

3084

3424

9728

4108

reflns collcd

161399

163660

175553

371503

141493

indep reflns

12613

13259

16109

35661

7138

obsd reflns [I > 2σ(I)]

10042

9563

11644

16972

5970

Rint

0.054

0.045

0.052

0.097

0.051

params refined R1

696 0.039

716 0.041

939 0.040

2530 0.103

447 0.042

wR2

0.108

0.102

0.104

0.314

0.127

S

1.064

1.000

0.997

0.991

1.068

ΔFmin (e Å 3) ΔFmax (e Å 3)

1.29 2.57

1.48

1.06

1.35

2.36 500

4.58 7.10

0.87 1.59

dx.doi.org/10.1021/cg2014072 |Cryst. Growth Des. 2012, 12, 499–507


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Table 2. Environment of the Uranium Atoms in Compounds 1 5: Selected Bond Lengths (Å) and Angles (deg)a 1

2

1.788(4)

O1 U1 O2

173.35(19)

1.793(4)

O5 U1 O6

70.21(14)

4

U1 O1

1.790(10)

O1 U1 O2

176.8(5)

U1 O2

1.817(10)

O9 U1 O11

72.6(3)

U1 O5

2.215(4)

O6 U1 O7

72.66(14)

U1 O9

2.203(9)

O11 U1 O13

72.8(3)

U1 O6

2.321(4)

O7 U1 O8

51.96(12)

U1 O11

2.310(9)

O13 U1 O14

51.3(3)

U1 O7 U1 O8

2.468(4) 2.572(4)

O8 U1 O9 O9 U1 O5

80.40(15) 85.16(15)

U1 O13 U1 O14

2.482(10) 2.508(9)

O14 U1 O15 O15 U1 O9

72.7(4) 90.5(4)

U1 O9

2.347(4)

U1 O15

2.370(11)

U2 O3

1.794(4)

O3 U2 O4

173.58(19)

U2 O3

1.748(10)

O3 U2 O4

176.7(4)

U2 O4

1.803(4)

O5 U2 O5i

71.05(16)

U2 O4

1.752(10)

O9 U2 O10

70.8(3)

U2 O5

2.252(4)

O5i U2 O6i

67.45(14)

U2 O9

2.237(9)

O10 U2 O12

69.3(4)

U2 O5i

2.295(4)

O6i U2 O11

72.83(15)

U2 O10

2.339(10)

O12 U2 O19

72.8(4)

U2 O6i

2.403(4)

O11 U2 O10

70.82(15)

U2 O12

2.400(13)

O19 U2 O16

68.5(4)

U2 O10 U2 O11

2.451(4) 2.481(4)

O10 U2 O5

78.49(14)

U2 O16 U2 O19

2.463(14) 2.496(13)

O16 U2 O9

79.0(4)

U1 O1

1.796(3)

O1 U1 O2

173.65(16)

U3 O5

1.819(9)

O5 U3 O6

174.8(5)

U1 O2

1.797(3)

O5 U1 O6

70.61(13)

U3 O6

1.787(9)

O9 U3 O10

71.5(3)

U1 O5

2.185(3)

O6 U1 O7

76.10(12)

U3 O9

2.277(8)

O10 U3 O17

78.8(4)

U1 O6

2.339(4)

O7 U1 O8

52.21(12)

U3 O10

2.263(11)

O17 U3 O20

68.2(3)

U1 O7

2.480(3)

O8 U1 O9

75.44(12)

U3 O11

2.384(9)

O20 U3 O11

71.6(3)

U1 O8

2.527(4)

O9 U1 O5

85.68(13)

U3 O17

2.432(9)

O11 U3 O9

69.9(3)

U1 O9 U2 O3

2.377(3) 1.798(4)

O3 U2 O4

172.58(16)

U3 O20 U4 O7

2.515(10) 1.779(9)

O7 U4 O8

170.6(7)

U2 O4

1.789(3)

O5 U2 O5i

70.62(14)

U4 O8

1.728(9)

O10 U4 O12

72.3(4)

U2 O5

2.264(3)

O5i U2 O6i

67.23(12)

U4 O10

2.288(11)

O12 U4 O21

70.8(6)

U2 O5i

2.310(3)

O6i U2 O11

75.21(12)

U4 O12

2.278(13)

O21 U4 O22

67.4(6)

U2 O6i

2.416(4)

O11 U2 O10

71.47(13)

U4 O18

2.309(12)

O22 U4 O18

70.2(5)

U2 O10

2.437(3)

O10 U2 O5

76.05(12)

U4 O21

2.40(2)

O18 U4 O10

80.5(4)

U2 O11

2.492(4)

U O1 U O2

1.784(3) 1.780(3)

O1 U O2 O3 U O8

177.89(12) 71.06(10)

U O3

2.360(3)

O8 U O5

72.14(10)

U O5

2.394(3)

i

O5 U O7

72.48(10)

U O7

2.298(2)

O7i U O7

67.79(11)

i

U O7

2.339(3)

O7 U O3

76.53(9)

U O8

2.486(3)

Symmetry codes: 1: i =

x, 2

3

a

U1 O1 U1 O2

y, 2

z; 2: i = 1

x, 1

y, 1

5

z; 3: i = 2

[UO2(HL3)(OH)(HCOO)(H2O)]2 3 2CB6 3 2DMF 3 14H2O (3). CB6 3 5H2O (11 mg, 0.01 mmol), a 10-fold excess of UO2(NO3)2 3 6H2O (50 mg, 0.10 mmol) and HL3 (15 mg, 0.10 mmol), DMF (0.5 mL), and demineralized water (1.2 mL) were placed in a 15 mL tightly closed glass vessel and heated at 180 °C under autogenous pressure. Light yellow crystals of complex 3, mixed with a white powder, appeared in low yield within one week.

x, 1

U4 O22

2.578(16)

U O1 U O2

1.775(4) 2.453(3)

O1 U O1i O2 U O3

180 52.75(9)

U O3

2.477(3)

O3 U O2j

67.25(9)

y, 1

z; 5: i = x, y, 3/2

z; j = 1

y, x

y + 1, z.

Crystallography. The data were collected at 150(2) K on a Nonius Kappa-CCD area detector diffractometer8 using graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). The crystals were introduced into glass capillaries with a protecting “Paratone-N” oil (Hampton Research) coating. The unit cell parameters were determined from 10 frames, then refined on all data. The data (combinations of j- and ωscans giving complete data sets up to θ = 28.7° (25.7° for 4) and a minimum redundancy of 4 for 90% of the reflections) were processed with HKL2000.9 Absorption effects were corrected empirically with the program SCALEPACK.9 The structures were solved by direct methods (1 4) or Patterson map interpretation (5) with SHELXS-97, expanded by subsequent Fourier-difference synthesis, and refined by full-matrix least-squares on F2 with SHELXL-97.10 All non-hydrogen atoms were refined with anisotropic displacement parameters. Some lattice water molecules were given 0.5 occupancy factors in order to retain acceptable displacement parameters and/or to account for too close contacts. The hydrogen atoms bound to oxygen and nitrogen atoms in 1 3 and 5 were found on Fourier-difference maps, except for those of N15 in 1 (which were introduced at ideal positions) and those of some solvent water molecules, but they were neither found, nor introduced, in 4; the carbon-

[(UO2)4(HL3)2(L3)O2(OH)2(H2O)4] 3 2CB6 3 0.5CB8 3 HL3 3 NO3 3 20H2O (4). CB6 3 5H2O (11 mg, 0.01 mmol), a 10-fold excess of

UO2(NO3)2 3 6H2O (50 mg, 0.10 mmol), HL3 (15 mg, 0.10 mmol) and CsNO3 (20 mg, 0.10 mmol), and demineralized water (1.5 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, mixed with a white powder, appeared in very low yield within one week. [UO2(HL4)(L4)2] 3 3CB6 3 16H2O (5). CB6 3 5H2O (11 mg, 0.01 mmol), a 10-fold excess of UO2(NO3)2 3 6H2O (50 mg, 0.10 mmol) and HL4 3 HCl (19 mg, 0.10 mmol), and demineralized water (1.5 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, mixed with a brownish amorphous powder, appeared in very low yield overnight. Attempts to increase the yield by prolonged heating were unsuccessful. 501



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Crystal data and structure refinement parameters are given in Table 1 and selected bond lengths and angles are in Table 2. The molecular plots were drawn with ORTEP-311 and the polyhedral representations with VESTA.12

Figure 1. Top: View of the uranyl complex in 1. Displacement ellipsoids are drawn at the 50% probability level. Carbon-bound hydrogen atoms are omitted. Symmetry code: i = x, 2 y, 2 z. Middle and bottom: Two views of the packing. The uranium coordination polyhedra are shown. Solvent molecules and hydrogen atoms are omitted. 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 (1.5 for CH3). Because of the low quality of the crystals and the large size of the asymmetric unit (2530 parameters refined), the structure of 4 could not be determined with a high degree of precision; several parts of this structure are badly resolved, and restraints on bond lengths, angles and/or displacement parameters had to be applied, particularly in the uncoordinated HL3 molecule, and two aromatic rings were refined as idealized hexagons; large voids in the lattice likely indicate the presence of other, unresolved water solvent molecules.

’ RESULTS AND DISCUSSION The complexes [H2NMe2]2[(UO2)2(L1)2O(OH)(H2O)]2 3 CB6 3 15H2O (1) and [H2NMe2]2[(UO2)2(L2)2O(OH)(H2O)]2 3 CB6 3 17H2O (2) both involve benzoic acid with an amino group in the para position, with an additional methyl group in the meta position being present in 2. The latter has little influence and both compounds can be considered to be isostructural. Both were obtained with dimethylformamide (DMF) being added in the reaction medium, so as to improve dissolution of the aminobenzoic acid. Under the conditions used, DMF undergoes hydrolysis to give formic acid and dimethylamine, as was often previously observed, not necessarily under hydrothermal conditions, but always in the presence of metal ions which are possibly catalysts for this reaction.7f,g,13 As a consequence, dimethylammonium or formate ions are often present in the complexes formed,7f,g and this is the case in 1 and 2, which contain H2NMe2+ counterions. The centrosymmetric, bis(μ3-oxo) tetranuclear uranyl complex found in both compounds, and represented in Figure 1 for complex 1, is a frequent motif in uranyl chemistry, which is found in many molecular species7a,14 and also in coordination polymers including CB6.7f The uranyl ions in 1 and 2 are laterally bridged by two hydroxide ions and two k2-O,O'-L1 anions. Two other L1 ligands are chelating U1 and its image by the inversion center, while two water molecules complete the coordination sphere of the other two uranium atoms, all metal ions being thus in pentagonal bipyramidal environments. The U O bond lengths, averaged over both complexes, for oxo, hydroxo, bridging carboxylate, chelating carboxylate, and water ligands, which amount to 2.25(4), 2.37(4), 2.40(4), 2.51(4), and 2.487(5) Å, respectively, are unexceptional. The four amino groups point toward the exterior of the nearly planar tetranuclear unit, but, being unprotonated, they are not involved in any interaction with the CB6 molecules. Instead, they form hydrogen bonds with carboxylate oxygen atoms, uranyl oxo groups, and water molecules. The two portals of the centrosymmetric CB6 molecules are occupied by the dimethylammonium counterions, which are hydrogen bonded to two carbonyl groups [N 3 3 3 O and H 3 3 3 O distances, and N H 3 3 3 O angles are in the ranges 2.801(12) 2.903(6) Å, 1.98 2.10 Å, and 150 154°, respectively]. Although both amine and ammonium groups are hydrogen bond donors, it is unsurprising that CB6 associates preferentially with the ionic species through charge dipole interactions, since the latter are predominant in CB6 ammonium host guest complexes.2 The lack of association between the uranyl complex and CB6 is thus a consequence of the use of DMF. Unfortunately, no crystalline material could be obtained in these cases, when the reaction was performed in pure water. The packing in 1 and 2 displays a parallel arrangement of the CB6 molecules, which are stacked in columns directed along the a axis, while the uranyl complex moieties are tilted with respect to one another so as to build a herringbone pattern when viewed down the c axis (Figure 1). When projected onto the bc plane, the uranyl complexes appear to be arranged in a square grid pattern, with the CB6 column axis coinciding with the center of the grid voids. The complex with the 4-aminomethyl-substituted ligand HL3, [UO2(HL3)(OH)(HCOO)(H2O)]2 3 2CB6 3 2DMF 3 14H2O (3), was also obtained in the presence of DMF, but, fortunately, dimethylammonium ions are not present in the final compound, which however contains formate anions, the other product of 502



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Figure 2. Top: View of the supramolecular assembly in 3. Displacement ellipsoids are drawn at the 30% probability level. Carbon-bound hydrogen atoms are omitted. Hydrogen bonds are shown as dashed lines. Symmetry code: i = 2 x, 1 y, 1 z. Bottom: View of one sheet down the [3 0 2] axis with water solvent molecules and hydrogen atoms omitted.

DMF hydrolysis. Only one uranyl ion is present in the asymmetric unit, which is bound to a monodentate carboxylate group from the HL3 ligand and one from the formate ion, while bridging hydroxide ions result in the formation of a centrosymmetric dimer (Figure 2). One water molecule completes the five-coordinate equatorial environment. The average U O bond lengths for carboxylate and hydroxo ligands are 2.377(17) and 2.32(2) Å, respectively. Intramolecular hydrogen bonds link the hydroxide ion to the uncomplexed carboxylate oxygen atom of HL3 and the water molecule to the uncoordinated oxygen atom of formate. The HL3 ligand is in its zwitterionic form, and this, together with the absence of other ammonium groups, enables HL3 to come into contact with CB6 through its ammonium substituent. The nitrogen atom N1 is at a distance of 0.082(5) Å from the portal mean plane, and it forms hydrogen bonds with the carbonyl atoms O9 and O11, and with the oxygen atom of a DMF molecule included in the CB6 cavity [N 3 3 3 O and H 3 3 3 O distances, and N H 3 3 3 O angles are in the ranges 2.705(7) 2.890(6) Å, 1.99 2.17 Å, and 126 159°, respectively]. Large, dumbbell-shaped supramolecular assemblies are thus formed, which consist of two terminal CB6 molecules held by the central dinuclear uranyl moiety. These assemblies are stacked so as to form layers in which the free portal of each CB6 molecule is directed toward the side of the CB6 molecule of a neighboring unit, so that CH 3 3 3 O hydrogen bonds are

formed (shorter C 3 3 3 O and H 3 3 3 O distances, 3.07 and 2.20 Å, respectively). Another synthesis with the same ligand HL3, in the absence of DMF, but with CsNO3 being added, gave the complex [(UO2)4 (HL3)2 (L3)O 2 (OH)2 (H 2 O)4 ] 3 2CB6 3 0.5CB8 3 HL3 3 NO 3 3 20H 2 O (4). Only a few crystals of quite poor quality were obtained, and the large structure (284 independent nonhydrogen atomic positions) could only be determined with moderate accuracy. The main features are however unambiguous and deserve some comments in the present context. CB8 is present in the final compound, as in previously reported complexes obtained from CB6,7a,f which likely indicates the presence of the former as an impurity in CB6 and accounts for the low yield observed. The asymmetric unit corresponds to one formula unit, in which the uranyl ions are assembled into a bis(μ3-oxo)-centered tetranuclear cluster devoid of any true symmetry (Figure 3). Atom U1 is chelated by a carboxylate group, while two other L3 /HL3 ligands are bridging the pairs of atoms U1, U2 and U3, U4. Two hydroxide ions (O11, O12) provide additional bridging. Curiously, instead of another chelating HL3 ligand, two water molecules complete the coordination sphere of U4. U2 and U3 are also bound to one water molecule each, all uranium atoms being thus in pentagonal bipyramidal environments. The average U O bond lengths for oxo, hydroxo, bridging carboxylate, chelating carboxylate, and water ligands are unexceptional, at 503



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Figure 3. Top: View of the supramolecular assembly in 4. Symmetry code: i = x + 1, 3/2 y, z 1/2. Displacement ellipsoids are drawn at the 30% probability level. Hydrogen atoms are omitted, and possible hydrogen bonds are shown as dashed lines. Middle: View of the one-dimensional arrangement. Bottom left: The same viewed end-on. Bottom right: View of the CB8 molecule with included HL3. Symmetry code: i = 1 x, 2 y, 1 z.

translations along the a and b axes. The ammonium nitrogen atoms are not all identically located with respect to the portals, with distances of 0.346(12), 1.79(3), and 0.081(12) Å for N1, N2, and N3, respectively. As a consequence, N1 and N3 make three and N2 only two possible hydrogen bonding contacts with carbonyl oxygen atoms, with N 3 3 3 O distances in the range 2.80(3) 2.97(2) Å. However, the hydrogen atoms were not found in this structure, and it cannot be known with certainty if N2 is the unprotonated atom (which is likely) or if the protons

2.27(4), 2.34(5), 2.39(6), 2.495(13), and 2.50(6) Å, respectively. Although this tetranuclear motif is very close to that encountered in complexes 1 and 2, apart from the missing chelating ligand, the protonation of two amine groups out of three (for charge balance) and the absence of other ammonium ions in the reaction medium enable interactions between L3 /HL3 and CB6 to take place, as in complex 3. Three CB6 molecules are thus held around the tetranuclear unit, with one of them, corresponding to N3, being the image of that bonded to N2 through a glide plane followed by 504



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Figure 4. Top: View of the supramolecular assembly in 5. Displacement ellipsoids are drawn at the 50% probability level. Carbon-bound hydrogen atoms are omitted. Hydrogen bonds are shown as dashed lines. Symmetry codes: i = x, y, 3/2 z; j = 1 y, x y + 1, z; k = y x, 1 x, z. Bottom: View of the packing with solvent molecules and hydrogen atoms omitted.

are disordered over the three amine groups. Due of the bridging CB6 molecule bound to one cluster by each of its two portals, a one-dimensional supramolecular assembly is built, which runs along the [2 0 1] axis (Figure 3). When viewed along the chain axis, the arrangement consists of a central row of tetranuclear clusters surrounded on each side by the bridging CB6 molecules,

and with the pendent CB6 units located in two rows close to one another on the same side of the chain. The compound also contains an independent CB8 molecule located around an inversion center, with two included and probably hydrogen bonded (but very badly resolved) HL3 molecules (Figure 3), which are involved together in a π-stacking interaction 505


Crystal Growth & Design (centroid 3 3 3 centroid distance 3.76 Å, offset 0.39 Å). The stacking of the one-dimensional assemblies and CB8 molecules results in a very intricate packing. The fourth ligand used, HL4, is the only one in which the amine group is not in the para position with respect to the carboxylic group. Instead, the amine and hydroxyl groups occupy both meta positions. In the complex obtained, [UO2(HL4)(L4)2] 3 3CB6 3 16H2O (5), which crystallizes in the hexagonal system, the uranium atom is located on a site of 6 symmetry, and it is chelated by three equivalent carboxylate groups (Figure 4), with an unexceptional average U O bond length of 2.465(12) Å; the uranium environment is thus hexagonal bipyramidal. Three protons were found on atom N1 during structure refinement (as well as the hydroxylic proton), whereas charge balance requires one protonated and two deprotonated ligands. It was assumed that the extra proton was disordered over the three amine sites, and the occupancy factors of the protons were chosen accordingly. The neutral [UO2(HL4)(L4)2] complex is located in a symmetry plane, which bisects the CB6 molecule. The latter is associated with the ammonium/amine group, with the nitrogen atom located at 0.161(4) Å from the mean portal plane (on the exterior side) and involved in possible hydrogen bonds with four carbonyl groups [N 3 3 3 O and H 3 3 3 O distances, and N H 3 3 3 O angles are 2.963(4), 2.18 Å, and 136° for the bifurcated bond with O5 and its symmetry equivalent, and 2.895(3), 2.07 Å, and 155° for the two bonds with O7 and its symmetry equivalent]. The hydroxyl group is hydrogen bonded to a solvent water molecule, which is possibly bound itself to a carbonyl group, thus probably bringing only a very minor contribution to the HL4/CB6 interactions. A discrete, large triangular assembly is thus formed, with a side length of ca. 26 Å. The packing of these supramolecular trimeric units displays cylindrical channels along the c axis, which are occupied by the solvent molecules (Figure 4).

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the metal ions and CB6 molecules (as iminodiacetic acid and α-amino acids in the case of lanthanide ions5,6). They give mono-, di-, or tetranuclear uranyl complexes of quite usual, planar geometry, around which the CB6 molecules are arranged. The overall architecture is imposed by the uranyl complexes, which can thus be viewed as efficient assemblers of CB6 units.

’ ASSOCIATED CONTENT

bS

Supporting Information. 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.

’ AUTHOR INFORMATION Corresponding Author

*E-mail: [email protected].

’ ACKNOWLEDGMENT The Direction de l’Energie Nucleaire of the CEA is thanked for its financial support through the Basic Research Program RBPCH. ’ 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. Incl. 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) Mock, W. L.; Shih, N. Y. J. Org. Chem. 1983, 48, 3618. (b) Freeman, W. A. Acta Crystallogr., Sect. B 1984, 40, 382. (c) Mock, W. L.; Shih, N. Y. J. Org. Chem. 1986, 51, 4440. (d) Mock, W. L.; Pierpont, J. J. Chem. Soc., Chem. Commun. 1990, 1509. (3) (a) Jeon, Y. M.; Whang, D.; Kim, J.; Kim, K. Chem. Lett. 1996, 503. (b) Kim, K.; Jeon, W. S.; Kang, J. K.; Lee, J. W.; Jon, S. Y.; Kim, T.; Kim, K. Angew. Chem., Int. Ed. 2003, 42, 2293. (c) Huang, W. H.; Zavalij, P. Y.; Isaacs, L. Org. Lett. 2008, 10, 2577. (d) Kim, Y.; Kim, H.; Ko, Y. H.; Selvapalam, N.; Rekharsky, M. V.; Inoue, H.; Kim, K. Chem. Eur. J. 2009, 15, 6143. (4) (a) Whang, D.; Jeon, Y. M.; Heo, J.; Kim, K. J. Am. Chem. Soc. 1996, 118, 11333. (b) Whang, D.; Kim, K. J. Am. Chem. Soc. 1997, 119, 451. (c) Whang, D.; Heo, J.; Kim, C. A.; Kim, K. Chem. Commun. 1997, 2361. (d) Roh, S. G.; Park, K. M.; Park, G. J.; Sakamoto, S.; Yamaguchi, K.; Kim, K. Angew. Chem., Int. Ed. 1999, 38, 638. (e) Lee, E.; Heo, J.; Kim, K. Angew. Chem., Int. Ed. 2000, 39, 2699. (f) Lee, E.; Kim, J.; Heo, J.; Whang, D.; Kim, K. Angew. Chem., Int. Ed. 2001, 40, 399. (g) Kim, K. Chem. Soc. Rev. 2002, 31, 96. (h) Park, K. M.; Whang, D.; Lee, E.; Heo, J.; Kim, K. Chem. Eur. J. 2002, 8, 498. (i) Wang, Z. B.; Zhao, M.; Li, Y. Z.; Chen, H. L. Supramol. Chem. 2008, 20, 689. (j) Zeng, J. P.; Cong, H.; Chen, K.; Xue, S. F.; Zhang, Y. Q.; Zhu, Q. J.; Liu, J. X.; Tao, Z. Inorg. Chem. 2011, 50, 6521. (5) Thuery, P. Inorg. Chem. 2010, 49, 9078. (6) Thuery, P. Inorg. Chem. 2011, 50, 10558. (7) (a) Thuery, P. Cryst. Growth Des. 2008, 8, 4132. (b) Thuery, P. CrystEngComm 2009, 11, 1150. (c) Thuery, P. Inorg. Chem. 2009, 48, 825. (d) Thuery, P. Cryst. Growth Des. 2009, 9, 1208. (e) Thuery, P.; Masci, B. Cryst. Growth Des. 2010, 10, 716. (f) Thuery, P. Cryst. Growth Des. 2011, 11, 2606. (g) Thuery, P. Cryst. Growth Des. 2011, 11, 3282. (8) Hooft, R. W. W. COLLECT; Nonius BV: Delft, The Netherlands, 1998. (9) Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307.

’ CONCLUSION Among the five uranyl ion complexes with amino- or ammoniobenzoates reported herein, three display ammonium CB6 associations, these being absent in the cases where the amine group is unprotonated and a competing ammonium species is present. These associations originate in ion dipole and hydrogen bonding interactions, but the hydrophobic effects that are present for the much used diaminoalkane derivatives are absent since no part of the molecule is included in the CB6 cavity. The supramolecular assemblies thus formed display different geometries, being either dimeric and dumbbell-shaped (3), one-dimensional polymeric with both bridging and pendent CB6 molecules (4), or discrete and triangular (5). These assemblies, and particularly the polymeric one, are reminiscent of the species generated through molecular recognition in the molecular tectonics approach.15 In complexes 3 5, the arrangement of the amino/ammoniobenzoate ligands around the uranyl ion governs the location of the CB6 molecules, and it is notable that the frequent arrangement of CB6 into columns or sheets is not found here. This is in contrast to the architectures often observed in compounds comprising uranyl ion complexes and coordinated or free CB6 molecules, in which the typical geometries of both subunits are retained. Because of the strong tendency for uranyl ions to give planar or undulated ribbons or sheets, owing to the equatorial positioning of its ligands, it is frequent to observe in such compounds an alternation of uranyl-containing sheets and CB6 layers or columns.7f,g The present ligands are different from those used in the previous studies since they are heterodifunctional and able to bridge 506



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(10) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112. (11) Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565. (12) Momma, K.; Izumi, F. J. Appl. Crystallogr. 2008, 41, 653. (13) See, for example:(a) Buckingham, D. A.; Harrowfield, J. M.; Sargeson, A. M. J. Am. Chem. Soc. 1974, 96, 1726. (b) Paulet, C.; Loiseau, T.; Ferey, G. J. Mater. Chem. 2000, 10, 1225. (c) Chen, W.; Wang, J. Y.; Chen, C.; Yue, Q.; Yuan, H. M.; Chen, J. S.; Wang, S. N. Inorg. Chem. 2003, 42, 944. (d) Ganesan, S. V.; Lightfoot, P.; Natarajan, S. Solid State Sci. 2004, 6, 757. (e) Harrowfield, J. M.; Skelton, B. W.; White, A. H.; Wilner, F. R. Inorg. Chim. Acta 2004, 357, 2358. (f) Zhao, J.; Li, J.; Ma, P.; Wang, J.; Niu, J. Inorg. Chem. Commun. 2009, 12, 450. (g) Bilyk, A.; Dunlop, J. W.; Fuller, R. O.; Hall, A. K.; Harrowfield, J. M.; Hosseini, M. W.; Koutsantonis, G. A.; Murray, I. W.; Skelton, B. W.; Stamps, R. L.; White, A. H. Eur. J. Inorg. Chem. 2010, 2106. (14) (a) Van den Bossche, G.; Spirlet, M. R.; Rebizant, J.; Goffart, J. Acta Crystallogr., Sect. C 1987, 43, 837. (b) Turpeinen, U.; H€am€al€ainen, R.; Mutikainen, I.; Orama, O. Acta Crystallogr., Sect. C 1996, 52, 1169. (c) Thuery, P.; Nierlich, M.; Souley, B.; Asfari, Z.; Vicens, J. J. Chem. Soc., Dalton Trans. 1999, 2589. (d) Gerasko, O. A.; Samsonenko, D. G.; Sharonova, A. A.; Virovets, A. V.; Lipkowski, J.; Fedin, V. P. Russ. Chem. Bull. 2002, 51, 346. (e) Yu, Z. T.; Li, G. H.; Jiang, Y. S.; Xu, J. J.; Chen, J. S. Dalton Trans. 2003, 4219. (f) Crawford, M. J.; Mayer, P.; N€oth, H.; Suter, M. Inorg. Chem. 2004, 43, 6860. (g) Harrowfield, J. M.; Skelton, B. W.; White, A. H. C. R. Chim. 2005, 8, 169. (h) Charushnikova, I. A.; Krot, N. N.; Polyakova, I. N.; Makarenkov, V. I. Radiokhimiya 2005, 47, 219. (i) Borkowski, L. A.; Cahill, C. L. Cryst. Growth Des. 2006, 6, 2248. (j) Hennig, C.; Servaes, K.; Nockemann, P.; Van Hecke, K.; Van Meervelt, L.; Wouters, J.; Fluyt, L.; G€orller-Walrand, C.; Van Deun, R. Inorg. Chem. 2008, 47, 2987. (k) Rodríguez-Dieguez, A.; Mota, A. J.; Seco, J. M.; Palacios, M. A.; Romerosa, A.; Colacio, E. Dalton Trans. 2009, 9578. (15) Hosseini, M. W. Acc. Chem. Res. 2005, 38, 313.

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Uranyl Ion Complexes with Ammoniobenzoates as Assemblers for

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