Effect of the proximal secondary sphere on the self-assembly of tetrahedral zinc-oxo clusters

Abstract

Metal-oxo clusters can serve as directional and rigid building units of coordination and noncovalent supramolecular assemblies. Therefore, an in-depth understanding of their multi-faceted chemistry is vital for the development of self-assembled solid-state structures of desired properties. Here we present a comprehensive comparative structural analysis of isostructural benzoate, benzamidate, and new benzamidinate zinc-oxo clusters incorporating the [O,O]-, [O,NH]- and [NH,NH]-anchoring donor centers, respectively. We demonstrated that the NH groups in the proximal secondary coordination sphere are prone to the formation of intermolecular hydrogen bonds, which affects the packing of clusters in the crystal structure. Coordination sphere engineering can lead to the rational design of new catalytic sites and novel molecular building units of supramolecular assemblies.

A New Look at Molecular and Electronic Structure of Homoleptic Diiron(II,II) Complexes with N,N‐Bidentate Ligands: Combined Experimental and Theoretical Study

“…The second‐sphere non‐covalent interactions often operate in concert with the primary donor‐acceptor bonds, which provides opportunities for the rational manipulation of the molecular and supramolecular structure of metal complexes [63,64] . It seems reasonable that the intermolecular non‐covalent interactions may be responsible for the different forms of complexes 1 and 2 .…”

“…[60][61][62] The second-sphere non-covalent interactions often operate in concert with the primary donor-acceptor bonds, which provides opportunities for the rational manipulation of the molecular and supramolecular structure of metal complexes. [63,64] It seems reasonable that the intermolecular non-covalent interactions may be responsible for the different forms of complexes 1 and 2. The paddlewheel-type complex 1 crystallises in the C2/c space group, and its supramolecular arrangement is governed via a system of cooperative intermolecular CÀ H•••π interactions (Figure 3c).…”

Tetrahedral M4(μ4-O) Motifs Beyond Zn: Efficient One-Pot Synthesis of Oxido–Amidate Clusters via a Transmetalation/Hydrolysis Approach

“… 34 − 37 Another approach based on well-defined precursors utilizes diorganozinc species, which are reacted with the appropriate proligand, and then are exposed to dioxygen 38 − 40 or undergo hydrolysis by addition of a stoichiometric amount of water ( Figure 2 b). 3 , 5 , 6 , 16 , 18 , 19 , 21 , 41 − 44 In the hydrolytic transformation, the high Brønsted basicity of alkylzinc moieties is not only used to generate O 2– ions but also facilitates initial deprotonation of the proligand. This approach enabled the synthesis of μ 4 -oxido complexes incorporating a wide range of organic ligands, namely, carboxylates, 5 , 16 , 21 phosphinates, 18 , 19 , 42 amidates, 23 amidinates, 6 , 26 , 41 , 43 and guanidinates.…”

“… 3 , 5 , 6 , 16 , 18 , 19 , 21 , 41 − 44 In the hydrolytic transformation, the high Brønsted basicity of alkylzinc moieties is not only used to generate O 2– ions but also facilitates initial deprotonation of the proligand. This approach enabled the synthesis of μ 4 -oxido complexes incorporating a wide range of organic ligands, namely, carboxylates, 5 , 16 , 21 phosphinates, 18 , 19 , 42 amidates, 23 amidinates, 6 , 26 , 41 , 43 and guanidinates. 44 Despite the wide scope of applied [Zn 4 (μ 4 -O)] 6+ core coating ligands, this relatively universal approach for Zn–oxido complexes is essentially non-transferable to the related transition-metal systems.…”

“…Molecular metal-oxido clusters have gained attention as versatile building units of a wide variety of functional materials based on both coordination , and noncovalent supramolecular networks. , The most prominent subsets of metal-oxido clusters include trinuclear μ 3 -oxido-centered complexes, tetranuclear μ 4 -oxido clusters, and multinuclear polyoxidometalates (POMs) (Figure a). Among them, clusters comprising a highly symmetrical tetrahedral [M 4 (μ 4 -O)] 6+ core (M = divalent metal) stabilized by six monoanionic bidentate organic ligands are of particular interest due to their multifaceted chemistry arising from the presence of several spots of structural tailorability, including divalent metal centers in the tetrahedral core, the character of anchoring groups, and the organic backbone of ligands in the secondary coordination sphere (Figure b). , Such diversity of structural features results in tuneable optoelectronic and coordination properties, which turns μ 4 -oxido compounds into suitable candidates for magnetic, luminescent, − and catalytic − materials. Moreover, [M 4 (μ 4 -O)­L 6 ]-type complexes can be regarded as discrete soluble intermediates between simple monomers and polymeric lattices of various hybrid organic–inorganic architectures.…”