Ancillary Ligands and Spectator Cations as Controlling Factors in the Construction of Coordination and Hydrogen-Bonded Networks with thetert-Bu-CC⊃Agn(n=4, 5) Supramolecular Synthon

Structural diversity of copper(I) alkynyl cluster-based coordination polymers utilizing bifunctional pyridine carboxylic acid ligands

The utilization of bifunctional ligands, specifically pyridine carboxylic acids, endowed with dual coordination sites, has been instrumental in the assembly of polymer materials. The ambidentate characteristics of these ligands play a crucial role in shaping the structure and framework of cluster-based polymers. In this study, we have synthesized a diverse array of multidimensional copper(I) alkynyl cluster-based polymers (CACPs) by employing four distinct pyridine carboxylic acids - namely, isonicotinic acid (INA), 6-isoquinolinecarboxylic acid (IQL), 4-pyridin-4-yl-benzoic acid (4-PyBA), and 3-pyridin-4-yl-benzoic acid (3-PyBA) - as linking ligands. These pyridine carboxylic acids not only serve as protective ligands but also act as pivotal linkers in constructing the cluster-based framework materials, exerting significant influence on the overall framework structures. Furthermore, the incorporation of auxiliary ligands has been shown to markedly impact the structural integrity and framework architecture of the CACPs. This study elucidates the indispensable role of pyridine carboxylic acids in the construction and stabilization of cluster-based framework materials, thereby advancing the frontier of research in metal cluster-based framework material synthesis.

Na2C3O2: The First Crystalline Compound with the Elusive -C≡C-COO- Anion

By reaction of sodium electride or NaC2H with the anhydrous sodium salt of propiolic acid, Na(OOC-C≡C-H), in liquid ammonia crystalline powders of Na2C3O2 were obtained. The structure analysis based on synchrotron powder diffraction data revealed that Na2C3O2 crystallizes in a monoclinic unit cell (I2/a, Z=4) exhibiting the elusive Y-shaped -C≡C-COO- anion, which is unprecedented in a crystalline compound up to now. IR/Raman and solid-state NMR spectroscopic investigations with assignments supported by DFT-based ab initio calculations confirm this finding. Reaction with sodium electride led to a higher crystallinity of the product, but additionally a by-product apparently due to decomposition and polymerization of Na2C3O2 was formed. No such by-product was observed in the reaction with NaC2H, which turned out to be a milder metalation route. However, the product of the latter reaction is less crystalline.

Threefold Collaborative Stabilization of Ag14 -Nanorods by Hydrophobic Ti16 -Oxo Clusters and Alkynes: Designable Assembly and Solid-State Optical-Limiting Application

Ag nanoclusters have received increasing attention due to their atomically precise and diverse structures and intriguing optical properties. Nevertheless, the inherent instability of Ag nanoclusters has seriously hindered their practical application. In this work, for the first time, Ag clusters are collaboratively protected by hydrophobic Ti-oxo clusters and alkyne ligands. Initially, a pyramidal Ag₅ cluster terminated with ^t BuC≡C^- and CH₃ CN was inserted into the cavity of a Ti₈ -oxo nanoring to form Ag₅ @Ti₈ . To overcome the instability of acetonitrile-terminated silver site, such two Ag₅ @Ti₈ clusters could sandwich an Ag₄ unit to form Ag₁₄ -nanorod@Ti₁₆ -oxo-nanoring (Ag₁₄ @Ti₁₆ ), which is peripherally protected by fluorophenyl groups and alkyne caps. This threefold protected (hydrophobic fluorinated organic layer, Ti-O shell, and terminal alkyne ligands) Ag₁₄ @Ti₁₆ exhibits superhydrophobicity and excellent ambient stability, endowing it with solid-state optical limiting characteristics.

A one-dimensional infinite silver alkynyl assembly [Ag8(C[triple bond, length as m-dash]C t Bu)5(CF3COO)3(CH3CN)] n : synthesis, crystal structure and properties

A high-yield silver alkynyl assembly [Ag8(C[triple bond, length as m-dash]C t Bu)5(CF3COO)3(CH3CN)] n (1) constructed from [AgC[triple bond, length as m-dash]C t Bu] n ligand, CF3COOAg and CH3CN auxiliary ligands with a one-dimensional infinite chain structure has been obtained in one pot. Compound 1 has been well-defined and characterized. The photocurrent properties and the temperature-sensitive luminescent properties of 1 have been investigated.

Investigation of the Effect of a Mixed-Ligand on the Accommodation of a Templating Molecule into the Structure of High-Nucleus Silver Clusters

Advancement of the synthesis and control of the self-assembly process of new high-nucleus silver clusters with desired structures is important for both the material sciences and the many applications. Herein, three new silver clusters, 20-, 22-, and 8-nucleus, based on alkynyl ligands were constructed and their structures were confirmed by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analyses, and Fourier-transform infrared spectroscopy (FT-IR). For the first time, the trivalent tetrahedron anion of AsO₄^3-, as a template, and the surface ligand of Ph₂PO₂H, with new coordination modes, were employed in preparation of the silver clusters. The role of surface ligands and template anions in the size and structure of the clusters was investigated. The presence of the template in the structure of the clusters led to the formation of the high-nucleus clusters. Also, in this report, it was shown that the participation of the template in the assembly of a cluster can be controlled by the surface ligands. UV-vis absorption and luminescent properties of the clusters and the thermal stability of the 8-nucleus cluster were also studied.

Silver(i)-organic frameworks constructed from silver(i) 3,6-pyrazyldiethynide and 3,8-1,10-phenanthrolyldiethynide complexes

Two diynes bearing functional groups with different binding modes, 3,6-diethynylpyrazine (H₂L1) and 3,8-diethynyl-1,10-phenanthroline (H₂L2), were utilized as ligands to synthesize two new organometallic units, Ag₂L1·3AgNO₃ (1) and Ag₂L2·6AgNO₃ (2), in order to investigate the effect of the bridging and chelating modes of the ligands on the structures of networks constructed from silver-ethynide compounds. Structural studies show that in 1, silver-ethynide cluster units aggregate to form chair-like organometallic slides through Ag-N coordination bonds. These slides are linked through argentophilic interaction to generate novel 2D ladder-like layers, and are further bridged by nitrate anions to afford a 3D network in the solid state. It is observed that all the Ag ions in one layer interact to afford a 2D silver network. However, in 2, the silver-ethynide cluster units only interact to generate unique sine wave-like organometallic chains through argentophilic interaction, which are further connected by nitrate anions to form a 3D network. In the solid state, both 1 and 2 are luminescent at room temperature.

Iminophosphanes: Synthesis, Rhodium Complexes, and Ruthenium(II)-Catalyzed Hydration of Nitriles

Highly stable iminophosphanes, obtained from alkylating nitriles and reaction of the resulting nitrilium ions with secondary phosphanes, were explored as tunable P-monodentate and 1,3-P,N bidentate ligands in rhodium complexes. X-ray crystal structures are reported for both κ¹ and κ² complexes with the counterion in one of them being an unusual anionic coordination polymer of silver triflate. The iminophosphane-based ruthenium(II)-catalyzed hydration of benzonitrile in 1,2-dimethoxyethane (180 °C, 3 h) and water (100 °C, 24 h) and under solvent free conditions (180 °C, 3 h) results in all cases in the selective formation of benzamide with yields of up to 96%, thereby outperforming by far the reactions in which the common 2-pyridyldiphenylphosphane is used as the 1,3-P,N ligand.

Synthesis and characterization of non-bridging mono- and bis-σ-η1-alkynyl derivatives of the phosphido-bridged hexaplatinum core [Pt6(μ-PBut2)4(CO)4]2+

Several mono- or bis-alkynyl derivatives of the [Pt₆(μ-PBu^t₂)₄(CO)₄]²⁺ core, pivotal intermediates in the synthesis of new cluster-containing oligomers, were prepared and fully characterized.

A silver-alkynyl cluster encapsulating a fluorescent polyoxometalate core: enhanced emission and fluorescence modulation

A fluorescent polyoxometalate-based silver(i)-alkynyl cluster exhibits sensitivity towards high energy UV irradiation and selectivity for detection of S²⁻.