Reactant-Mediated Diversity in Uranyl Phosphonates

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.