Two uranyl–organic frameworks with pyridinecarboxylate ligands. A novel heterometallic uranyl–copper(II) complex with a cation–cation interaction

Series of Hydrated Heterometallic Uranyl-Cobalt(II) Coordination Polymers with Aromatic Polycarboxylate Ligands: Formation of U═O—Co Bonding upon Dehydration Process

“…The oxygen atoms of uranyl dioxo-cation (UO 2 2+ ) are rarely engaged with other metallic cations. Nevertheless, some cases of heterometallic interactions (MOU) are reported in coordination polymers with divalent transition metals such as Mn 2+ , , Co 2+ , , Cu 2+ , ,,,, Zn 2+ , and Cd 2+ . The distances CoO and UO observed in compound 1′ are close to the distances observed previously in the literature (UO; CoO). , They have an impact on the uranyl UO yl bond length: the free uranyl UO yl bond distance is 1.754(2) Å since the second uranyl UO yl bond distance is 1.796(2) Å, but it is also involved in the CoO yl linkage.…”

“…The crystallization of molecular species from aqueous solution using carboxylate ligand can help to fill this lack of information, especially if the selected organic linker occurs naturally. Regarding the literature, the association of uranyl and heterometal (M) such as a divalent transition metal or rare earth is particularly studied with heterofunctional linker molecules (carboxyphosphinates, phosphonate–carboxylates, − pyridine-carboxylates − ) or the addition of N-donor molecules. − The isolation of bimetallic UO 2 2+ –M coordination polymers with carboxylate ligands is also reported (M = Ni 2+ , ,− Co 2+ , , Cu 2+ , − Zn 2+ , ,, Ln 3+ ,− ).…”

Bimetallic Uranyl Organic Frameworks Supported by Transition-Metal-Ion-Based Metalloligand Motifs: Synthesis, Structure Diversity, and Luminescence Properties

“… The Cu II ion is in a six-coordinated distorted octahedral environment, with two N atoms from one bpdc 2– ligand, three O atoms from three coordinated water molecules, and, more interestingly, one uranyl oxo atom (O1) to fulfill the coordination sphere. This bonding type, which includes the connection of a uranyl oxo atom and a second metal center, is often called a cation–cation interaction. , The distorted octahedral environment of the Cu II center is thus occupied by an N 2 O 2 square in its equatorial plane, which involves one bpdc 2– ligand and two water molecules with short bonds, while another water molecule and a uranyl oxo O atom are approaching from the axial positions of Cu II . Each bpdc 2– ligand links two uranyl centers by two different carboxylate groups adopting one monodentate fashion and one bidentate chelating mode, respectively, and one Cu II center by two bipyridine N atoms (Scheme b), which forms a 1D [Cu­(UO 2 )­(bpdc)­(H 2 O) 3 ] n 2 n + chain.…”

Copper/Zinc-Directed Heterometallic Uranyl-Organic Polycatenating Frameworks: Synthesis, Characterization, and Anion-Dependent Structural Regulation

“…Uranyl-bearing complexes have played an important role in the research of actinide chemistry due to their rich structures, intriguing chemical or physical properties, and potential application in waste management and separation. − Uranyl coordination polymers usually possess one-dimensional (1D) or two-dimensional (2D) structures rather than three-dimensional (3D) frameworks because of the peculiar coordination sites of linear uranyl ion which only allows the binding of organic ligands in its equatorial plane. ,,− In order to construct 3D uranyl organic frameworks, one possible method is to add d-block transition metal cations which usually afford an octahedral coordination environment to the reaction systems. These cations can bind organic ligands or uranyl oxo groups through cation–cation interactions, which provide the feasibility to extend low dimensional structures into 3D frameworks. − Considering the challenge of combining two different metal centers in one complex for single-functional organic ligands, a multifunctional ligand that possesses different coordination sites which can selectively coordinate with uranyl or transition metal ions are often proposed. According to the hard-soft acid-base (HSAB) concept, uranyl ions are normally regarded to be hard acids and have high binding affinities toward O-donor groups such as carboxylate acid groups, while d-block transition metal ions are borderline acids, which prefer to bind some N-donor groups, for example, pyridyl groups. , On the basis of this principle, the idea of using O/N mixed ligands seems to be promising for the synthesis of uranyl-3d transition metal heterometallic coordination polymers. − …”