Favoring Framework Formation through Structure-Directing Effects in Uranyl Ion Complexes with 1,2,3,4-(Cyclo)butanetetracarboxylate Ligands

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

Six uranyl ion complexes with 1,2,3,4-cyclobutanetetracarboxylic acid (H4CBTC) and one with 1,2,3,4-butanetetracarboxylic acid (H4BTC) have been obtained under solvo-hydrothermal conditions in the presence of diverse, organic or metallic counterions. The different conformations found for the cyclic ligand (cis,trans,cis or trans,trans,trans in most cases, with one instance of cis,trans,trans), the diverse coordination modes adopted, and the presence of additional metal cations in some cases result in variations in dimensionality and topology of the complexes formed. Two complexes involve protonated azamacrocycles as counterions, [R,S-Me6cyclamH2][UO2(CBTC)] (1) and [cyclamH4][UO2(CBTC)]2 (2), where cyclam = 1,4,8,11-tetra-azacyclotetradecane and R,S-Me6cyclam = 7(R),14(S)-5,5,7,12,12,14-hexamethylcyclam, which crystallize as a one-dimensional (1D) ribbon-like coordination polymer and a two-dimensional (2D) network with sql topology, respectively, the counterions providing additional hydrogen bonding connectivity. The heterometallic complex [(UO2)2(HCBTC)2Cu(R,S-Me6cyclam)(H2O)2] (3) crystallizes as a 2D network with the V2O5 topology, in which the Cu II cations link uranyl-based 1D subunits, while [UO2(CBTC)Cu(bipy)(H2O)] (4) displays also a 2D arrangement in which the Cu II cations do not directly contribute to dimensionality increase. The high coordination number of Pb II in the heterometallic complexes [UO2Pb(CBTC)(H2O)]⋅0.5H2O (5) and [UO2Pb(BTC)(H2O)]⋅0.5H2O (6) allows the formation of intricate three-dimensional (3D) frameworks, with the presence of channels in 6; in both cases, columns of face-or edge-sharing lead(II) coordination polyhedra are found, with edge-or apex-sharing uranium coordination polyhedra attached to them. The homometallic complex [H2NMe2]4[(UO2)4(CBTC)3] (7) crystallizes as a cubic 3D framework with ctn topology different from the other cubic framework with tfg topology previously reported; the presence of channels in 7 results in the lowest packing index of the series. The uranyl emission spectra of compounds 1 and 2 display maxima positions of the vibronic fine structure peaks in agreement with those usually found for carboxylate complexes with uranyl O5 equatorial environments.

Domaines: Cristallographie; Chimie inorganique; Chimie de coordination

Pierre Thuéry, Youssef Atoini, Jack Harrowfield. Favoring Framework Formation through Structure-Directing Effects in Uranyl Ion Complexes with 1,2,3,4-(Cyclo)butanetetracarboxylate Ligands. Crystal Growth & Design, 2019, 19, pp.7. ⟨10.1021/acs.cgd.9b00546⟩. ⟨cea-02145077⟩