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A long‐standing question in electron transfer research concerns the number and identity of collective nuclear motions that drive electron transfer or localisation. It is well established that these nuclear motions are commonly gathered into a so‐called electron transfer coordinate. In this theoretical study, we demonstrate that both anti‐symmetric and symmetric vibrational motions are intrinsic to bridged systems, and that both are required to explain the characteristic shape of their intervalence charge transfer bands. Using the properties of a two‐state Marcus–Hush model, we identify and quantify these two coordinates as linear combinations of normal modes from ab initio calculations. This quantification gives access to the potential coupling, reorganization energy and curvature of the potential energy surfaces involved in electron transfer, independent of any prior assumptions about the system of interest. We showcase these claims with the Creutz–Taube ion, a prototypical Class III mixed valence complex. We find that the symmetric dimension is responsible for the asymmetric band shape, and trace this back to the offset of the ground and excited state potentials in this dimension. The significance of the symmetric dimension originates from geometry dependent coupling, which in turn is a natural consequence of the well‐established superexchange mechanism. The conceptual connection between the symmetric and anti‐symmetric motions and the superexchange mechanism appears as a general result for bridged systems. [ABSTRACT FROM AUTHOR]

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Ammonia and amine ligands are commonly assumed to be σ-only ligands in coordination chemistry, i.e. they are not expected to interact significantly with a metal via a π path. Ligand field analyses employing the Angular Overlap Model resulted in good fits to experimental data without a π parameter for ammonia ligands, thereby supporting this assumption. In this work, we challenge this assumption and suggest that it is an oversimplification. We use complete active space calculations for electronic structure analyses of copper ammine complexes that are in good agreement with the transitions observed in experimental UV-vis spectra. These findings lead to a reinterpretation of the experimental spectra that necessitates a significant π interaction of the ammonia ligands. The strength of the ammonia π interaction is evaluated by parameterizing the ligand field splittings of a series of metal hexammine complexes ([M(NH3)6]n+ with M = Cr, Mn, Fe, Co, Ni, Ru, Os and n = 2, 3) and selected tetrammine complexes ([M(NH3)4]n+ with M = Cr, Mn, Fe, Co, Ni and n = 2 or 3) with the Angular Overlap Model. The resulting π parameters show that ammonia is a π donor of similar strength as chloride. [ABSTRACT FROM AUTHOR]

Thiocarbohydrazone-based catalysts feature ligands that are potentially electrochemically active. From the synthesis point of view, these ligands can be easily tailored, opening multiple strategies for optimization, such as using different substituent groups or metal substitution. In this work, we show the possibility of a new strategy, involving the nuclearity of the system, meaning the number of metal centers. We report the synthesis and characterization of a trinuclear nickel-thiocarbohydrazone complex displaying an improved turnover rate compared with its mononuclear counterpart. We use DFT calculations to show that the mechanism involved is metal-centered, unlike the metal-assisted ligand-centered mechanism found in the mononuclear complex. Finally, we show that two possible mechanisms can be assigned to this catalyst, both involving an initial double reduction of the system. [ABSTRACT FROM AUTHOR]

The article discusses the presence of symmetric motion in bridged systems, which is responsible for the characteristic shape of the inter-valence charge transfer band. The authors demonstrate the close relationship between symmetric and anti-symmetric motions in mixed-valent systems. Another study mentioned in the article explores the binding of new mixed-valence cage-like polyoxidovanadate clusters to lysozyme. Additionally, the article reports on an all-inorganic metal-halide perovskite with a significant piezochromic range. [Extracted from the article]

The article titled "Titelbild: Symmetric Electron Transfer Coordinates are Intrinsic to Bridged Systems: An ab Initio Treatment of the Creutz–Taube Ion" discusses the presence of symmetric motion in bridged systems, which is responsible for the characteristic shape of the inter-valence charge transfer band. The authors, Adam Šrut, Benjamin J. Lear, and Vera Krewald, demonstrate the close relationship between symmetric and anti-symmetric motions in mixed-valent systems. Another article in the journal discusses the binding of new mixed-valence cage-like polyoxidovanadate clusters to lysozyme, while a third article reports on an all-inorganic metal-halide perovskite with a significant piezochromic range. [Extracted from the article]

The magnetic behavior of endohedrally transition-metal-doped tetrel clusters Sn 12 TM (TM = Cr, Mn, Fe) was investigated using a combined experimental and theoretical approach. Based on an improved experimental setup, the magnetic deflection was measured over a wide temperature range of T nozzle = 16-240 K. From a Curie analysis of the experimentally observed single-sided shift at high nozzle temperatures, the spin multiplicities and g -factors were determined. It was observed that all three nanoclusters analyzed are paramagnetic, with Sn 12 Mn being a sextet with g = 2.1 ± 0.1, while Sn 12 Cr is a quintet with the same g -factor and Sn 12 Fe is also a quintet but with a higher g -factor of 2.4 ± 0.1. In order to better understand the interplay between geometric and electronic structures and their influence on magnetism, a global geometry optimization was carried out, followed by a quantum-chemical analysis of the electronic structure using density functional theory (DFT) and wavefunction methods. The multi-reference calculations proved particularly important for Sn 12 Fe because DFT fails to correctly predict the value of the g -factor. To describe the electronic ground state of Sn 12 Fe, two reference configurations must be taken into account. A charge transfer from the Sn ligands to Fe manifests in very low-lying electronic excitations. These charge transfer excitations lead to a significant increase in the g -factor compared to the value of the free electron due to the large spin-orbit coupling constant of Sn. As a result, in contrast to Sn 12 Mn and Sn 12 Cr, the spin density of Sn 12 Fe is strongly delocalized over the entire cluster framework.