Intercalation of a range of phosphonic acids into [LiAl 2 (OH) 6 ]Cl‚H 2 O at pH 8 leads to cointercalation of both mono-and dianionic guest anions. Solid-state 31 P NMR data can be used to show that these materials exhibit a 31 P chemical shift that is intermediate between the values for the monoanionic and dianionic forms of the respective acids, suggesting that rapid proton exchange occurs between the intercalated anions. It is possible to calculate the relative amounts of mono-and dianionic species present using the observed averaged chemical shift of the intercalate phase. In the case of methylphosphonic acid, the ratio of mono-and dianionic species (MePO 3 H -/MePO 3 2-) is estimated to be 2.1. The intercalation of methyl-, ethyl-, phenyl-, and benzylphosphonic acids into [LiAl 2 (OH) 6 ]Cl‚H 2 O was studied using time-resolved, in situ energy-dispersive synchrotron X-ray diffraction. The rates of intercalation are significantly greater for methylphosphonic acid (MPA), ethylphosphonic acid (EPA), and benzylphosphonic acid (BPA) than for phenylphosphonic acid (PPA). The large BPA anions intercalate the most quickly, and MPA reacts more rapidly than EPA. Kinetic analyses of the rate data suggest that these are diffusion-controlled reactions. In situ X-ray diffraction experiments performed with slow addition of the guest have allowed observation of intermediate crystalline phases during the reactions with MPA and BPA. The intermediate phases can be indexed assuming a second-stage intercalation compound in which alternate interlayer regions are occupied by phosphonic acid and Clanions, respectively (Williams et al. Chem. Commun. 2003, 1816. The observation of these secondstage intermediates is very surprising, because staging in rigid layer lattices such as layered double hydroxides (LDHs) is highly unusual.

Four organically templated uranyl phosphonates, [C4N2H12][UO2F(PO3CH3)]2 (UPNO-1), [C4N2H12][UO2(PO3CH3)(PO2(OH)CH3)]2 (UPNO-2), [C4N2H12][(U2O4F3)(UO2F(H2O))(PO3C6H5)2]·2H2O (UPNO-3), and [C4N2H12]2[(UO2)5(PO3CH2C6H5)6(PO2(OH)CH2C6H5)2] (UPNO-4) have been synthesized under hydrothermal conditions. UPNO-1 contains doubly protonated piperazine templates, [C4N2H12]2+, residing between [UO2F(PO3CH3)]1- anionic layers. Distinct hydrophobic and hydrophilic regions are present between [UO2(PO3CH3)(PO2(OH)CH3)]1- layers in UPNO-2. The template is found in the hydrophilic interlayer space only, completely segregated from the methyl groups of the uranyl methylphosphonate layer, which protrude into the hydrophobic interlayer space. UPNO-3 contains [(U2O4F3)(UO2F(H2O))(PO3C6H5)2]2- layers separated by both piperazine templates, [C4N2H12]2+, and phosphonate phenyl groups, which exist in the same interlayer region. In UPNO-4 the region between [(UO2)5(PO3CH2C6H5)6(PO2(OH)CH2C6H5)2]4- layers is completely hydrophobic as a result of the large number of benzyl groups occupying the interlayer space. The template is found in voids within each layer. The structures of these compounds are dependent upon the reactant concentrations. Crystal data for the compounds are as follows:  UPNO-1, a = 6.9288(3) Å, b = 8.1174(4) Å, c = 14.8505(9) Å, β = 91.7173(19)°, monoclinic P21/n (no. 14), Z = 2; for UPNO-2, a = 10.0682(4) Å, b = 8.9121(3) Å, c = 12.9631(7) Å, β = 90.4901(15)°, monoclinic P21/a (no. 14), Z = 2; for UPNO-3, a = 6.7796(1), b = 17.2821(4) Å, c = 24.6754(6) Å, orthorhombic Pbcm (no. 57), Z = 4; and for UPNO-4, a = 11.4732(2) Å, b = 14.9097(2) Å, c = 15.4480(3) Å, α = 64.2307(6)°, β = 70.2105(7)°, γ = 84.136(1)°, triclinic P1̄ (no. 2), Z = 2.

The phase stability of organically templated uranium sulfates in the [UO(2)(CH(3)CO(2))(2).2H(2)O/homopiperazine/H(2)SO(4)] and [UO(2)(CH(3)CO(2))(2).2H(2)O/N,N-dimethylethylenediamine/H(2)SO(4)] systems has been studied using composition space. Two new compounds were formed in each system; [N(2)C(5)H(14)](2)[UO(2)(SO(4))(3)] (USO-17) and [N(2)C(5)H(14)][UO(2)(H(2)O)(SO(4))(2)] (USO-18) contain homopiperazine, and [N(2)C(4)H(14)][UO(2)(SO(4))(2)] (USO-19) and [N(2)C(4)H(14)][(UO(2))(2)(H(2)O)(SO(4))(3)].H(2)O (USO-20) contain N,N-dimethylethylenediamine. The relative stability of the products from each system is dependent upon the reactant mole fractions in the initial reaction gel. Crystal data: USO-17, a = 14.4975(3) A, b = 11.9109(3) A, c = 13.0157(3) A, beta = 110.475(1) degrees, monoclinic, C2/c (No. 15), Z = 4; for USO-18, a = 7.6955(2) A, b = 11.7717(3) A, c = 14.7038(4) A, orthorhombic, P22(1)2(1) (No. 18), Z = 4; for USO-19, a = 9.3322(1) A, b = 9.7743(2) A, c = 13.8897(3) A, orthorhombic, P2(1)2(1)2(1) (No. 19), Z = 4; and for USO-20, a = 11.2460(2) A, b = 10.5387(2) A, c = 17.0432(3) A, beta = 92.9884(6) degrees, monoclinic, P2(1)/c (No. 14), Z = 4.

Microporous solids have attracted considerable attention owing to optical, catalytic, or sorption properties. 1 The incorporation of metal centers into microporous materials has been extensively studied toward the goal of preparing compounds with the chemical and thermal stability and selectivity of zeolites. 2 Many chemical reactions can be facilitated by transition metal centers such as free-radical chemistry, redox chemistry, and photochemical reactions.The hydrothermal chemistry of uranium has been the subject of attention in recent years [3][4][5][6][7] owing to the potential structural diversity resulting from the high coordination numbers available to U 6+ and the existence of several desirable physical properties. 8 Despite this, few organically templated open-framework uranium materials are known; one phosphate, 4 one oxide, 5b one molybdate, 5c one fluoride, 6c one sulfate, 6i one phosphite, 6r and one silicate. 7 We report the phase-pure synthesis, crystal structure, and thermal stability analysis of the first microporous uranium phosphate fluoride, [N 2 C 6 H 14 ] 2 -[(UO 2 ) 6 (H 2 O) 2 F 2 (PO 4 ) 2 (HPO 4 ) 4 ]‚4H 2 O (MUPF-1). 9,10 Six distinct uranium sites are observed in MUPF-1, each of which is seven-coordinate in a pentagonal bipyramidal geometry. Each uranium(VI) cation is bound to two oxide ligands through short "uranyl" bonds. The [UO 2 ] 2+ bonds exhibit distances ranging between 1.765(8) and 1.795(8) Å, and O-U-O angles that range between 177.5(4) and 179.0(4)°. These values are near to the average reported values. 11 The five equatorial coordination sites around each uranium center differ. U(1), U(2), U(5), and U(6) are each bound to two oxide ligands that are shared between one UO 7 polyhedron and one PO 4 tetrahedron each, and three oxides that are shared between two UO 7 polyhedra and one PO 4 tetrahedron each. The equatorial coordination environment around U(3) and U(4) contains bonds to three oxides that are shared with PO 4 tetrahedra, one water molecule and one fluoride anion. The assignment of bound water molecules and fluoride anions was based upon bond length (2.299(8) and 2.306(8) Å versus 2.490(9) and 2.452(9) Å for U-F and U-O water bonds, respectively) and hydrogen-bonding interactions (see Figure 1), which are aligned along the a axis. Bond valence calculations 12,13 on MUPF-1, using uranium parameters from Burns et al.,11 resulted in values between 5.939 and 6.071 for the uranium centers. Six distinct phosphate sites exist in MUPF-1, each of which resides in the center of one of two types of phosphate tetrahedra. P(1) and P(6) are each bound to four oxide ligands that bridge to uranium centers, while P(2), P(3), P(4), and P(5) are each bound to three bridging and one protonated oxide.Three analogous [U 2 O 12 ] dimers, consisting of two edge-shared UO 7 polyhedra, are observed in MUPF-1.