Understanding the Influence of Terminal Ligands on the Electronic Structure and Bonding Nature in [Re₆(μ₃-Q₈)]²⁺ Clusters

Abstract

Since the synthesis of the first molecular cluster [Re6(μ3-Q8)X6](4-), the substitutional lability of the terminal ligands prompted new developments in their chemistry, making these molecular clusters a reasonable point of departure for building new materials. The development of novel inorganic materials of technological interest certainly requires an understanding of the electronic structure, bonding, spectroscopy, photophysical and structural properties of these clusters. Taking into account the potential applications in material sciences and the lack of systematization in the study of these kinds of clusters, the proposal of the present work is to perform a detailed theoretical study of the [Re6(μ3-Q8)X6](4-) (Q = S(2-), Se(2-), Te(2-); X = F(-), Cl(-), Br(-), I(-), CN(-), NC(-), SCN(-), NCS(-), OCN(-), NCO(-)) clusters based on the detailed description of the electronic structure of these complexes and the bonding nature between the [Re6(μ3-Q8)](2+) core and several donor-acceptor peripheral ligands. All this work was developed on the framework of the relativistic density functional theory, in which relativistic effects were incorporated by means of a two-component Hamiltonian with the zeroth-order regular approximation. To describe the relative stability of these complexes, we employed the global descriptors of chemical hardness and softness introduced by Pearson. Moreover, an analysis of bonding energetics was performed by combining a fragment approach to the molecular structure with the decomposition of the total bonding energy according to the Morokuma-Ziegler energy partitioning scheme. After an analysis of these results, we found in all cases an extensive ionic character in the bonding between the core and each peripheral ligand. The interaction between the halide ligand and the core gives about 75% ionic character, whereas the other ligands show a more covalent interaction due to effective synergic mechanisms. We conclude that the most stable clusters are those that present the stronger σ-donor terminal ligands, whereas the cluster stability starts to decrease when the π-acceptor effect will be stronger; this fact is directly related to the terminal ligand lability and the strong electrophilic character of the [Re6(μ3-Q8)](2+) core.

Advances in bonding and properties of inorganic systems from relativistic calculations in Latin America

“…This fact is directly related with the terminal ligand lability and the strong electrophilic character of the [Re 6 (μ 3 -Q 8 )] 2+ core. [131] 2.8 | Redox behavior , which is in good agreement with the value predicted theoretically (+0.28 V). [132] 2.9 | Luminescent properties…”

“…Therefore, the most stable clusters are those that present stronger σ‐donor terminal ligands, whereas cluster stability starts to decrease when the π‐acceptor effect is stronger. This fact is directly related with the terminal ligand lability and the strong electrophilic character of the [Re 6 (μ 3 ‐Q 8 )] 2+ core …”

Host–Guest Binding Hierarchy within Redox‐ and Luminescence‐Responsive Supramolecular Self‐Assembly Based on Chalcogenide Clusters and γ‐Cyclodextrin

“…Previous studies reported electrochemical properties of the [Re 6 Q 8 (CN) 6 ] 4− anions in non‐aqueous medium, such as acetonitrile or dichloromethane solvent showing that the 24‐electron {Re 6 Q 8 } 2+ cores undergo a quasi‐reversible one‐electron transfer leading to the 23‐electron oxidized species . Besides, the oxidizing ability of the {Re 6 Q 8 } 2+ core was revealed to be dependent on the σ donating character of the Q inner ligands that increases ongoing from S to Te atom . Surprisingly, electrochemical properties of the {Re 6 Q 8 } 2+ series in aqueous solution have never been reported while many supramolecular processes arise from the remarkable properties of water solvation.…”

“…[24] Besides, the oxidizing ability of the {Re 6 Q 8 } 2 + core was revealed to be dependento nt he s donating character of the Qi nner ligands that increases ongoing from StoT eatom. [25] Each cluster undergoes am onoelectronic wave observed at E1 = 2 = 0.820, 0.580 and 0.290 Vv ersus SCE for Q = S, Se and Te ,r espectively.S uch at rend appears fully consistentw ith previousr esults obtained in CH 3 CN but a % 0.2 Vs ystematic shift toward positive potential was observed in aqueous medium( see Table 2). Furthermore, variation of the anodic (E a ) and cathodic( E c )p eak currents exhibits af air linear dependence upon square root of the potentials can rate ffiffiffiffiffi SR p ,c onsistent with ad iffusion-controlled electron-transfer kinetic (see Supporting Information §6.1, Figure S11).…”

New Properties of a Bioinspired Pyridine Benzimidazole Compound as a Novel Differential Staining Agent for Endoplasmic Reticulum and Golgi Apparatus in Fluorescence Live Cell Imaging

“…All molecular structures were fully optimized by an analytical energy gradient method as implemented by Verluis and Ziegler (Echeverria et al, 2009; Ramírez-Tagle et al, 2010; Alvarado-Soto and Ramirez-Tagle, 2015; Bjorgaard et al, 2015), using the hybrid B3LYP functional and the standard Slater-type-orbital (STO) basis set with triple-ζ quality double plus polarization functions (TZ2P) for all the atoms (Rabanal-Leon et al, 2014; Zhang et al, 2016). Frequency analyses were performed after the geometry optimization to corroborate the minimum and to compare with experimental infrared spectra.…”