Structure-Directing Effects of Counterions in Uranyl Ion Complexes with Long-Chain Aliphatic α,ω-Dicarboxylates: 1D to Polycatenated 3D Species

Pierre Thuéry (1) , Youssef Atoini (2) , Jack Harrowfield (2)

1 LCMCE - Laboratoire de Chimie Moléculaire et de Catalyse pour l'Energie (ex LCCEF)
2 ISIS - Institut de Science et d'ingénierie supramoléculaires

Nine uranyl ion complexes were synthesized under (solvo-)hydrothermal conditions using α,ω-dicarboxylic acids HOOC-(CH2)n-2-COOH (H2Cn, n = 6-9) and diverse counterions. Complexes [PPh4][UO2(C6)(NO3)] (1) and [PPh4][UO2(C8)(NO3)] (2) contain zigzag one-dimensional (1D) chains, further polymerization being prevented by the terminal nitrate ligands. [PPh3Me][UO2(C7)(HC7)] (3) crystallizes as a 1D polymer with a curved section, hydrogen bonding of the uncomplexed carboxylic groups giving rise to formation of threefold interpenetrated two-dimensional (2D) networks. [PPh4][H2NMe2][(UO2)2(C7)3] (4) and [PPh3Me]2[(UO2)2(C8)3] (5) contain 1D chains, either ladderlike or containing doubly bridged dimers, while [PPh3Me]2[(UO2)2(C9)3]⋅2H2O (6) displays interdigitated, strongly corrugated honeycomb 2D nets. Ladderlike 1D polymers in [Cu(R,S-Me6cyclam)][(UO2)2(C7)2(C2O4)]⋅4H2O (7) are associated into columns by the hydrogen bonded counterions, whereas the [Ni(cyclam)] 2+ moieties are part of the 2D polymeric arrangement in [(UO2)2(C7)2(HC7)2Ni(cyclam)]⋅2H2O (8) due to axial coordination of the nickel(II) centre, hydrogen bonding mediated by water molecules generating a three-dimensional (3D) net. [(UO2)2K2(C7)3(H2O)]⋅0.5H2O (9) contains convoluted uranyl dicarboxylate 2D subunits which generate a 3D framework through 2D : 3D parallel polycatenation similar to that previously found in [NH4]2[(UO2)2(C7)3]⋅2H2O; further linking of these subunits is provided by bonding of the potassium cations to carboxylate and uranyl oxido groups. The solid state emission spectra of complexes 1-6 and 9 display maxima positions typical of hexacoordinated uranyl carboxylate complexes, but uranyl luminescence is quenched in 7. A solid-state photoluminescence quantum yield of 11.5% has been measured for complex 1, while those for compounds 3-6 and 9 are in the range of 2.0-3.5%.

Domaines: Cristallographie

Pierre Thuéry, Youssef Atoini, Jack Harrowfield. Structure-Directing Effects of Counterions in Uranyl Ion Complexes with Long-Chain Aliphatic α,ω-Dicarboxylates: 1D to Polycatenated 3D Species. Inorganic Chemistry, 2018, 58, pp.567-580. ⟨cea-01965731⟩