European Journal of Inorganic Chemistry最新文献

In this work, we present a novel approach to metal-assisted chemical etching (MACE) of silicon using copper(II) ions in mixtures of hydrofluoric acid (HF) and hydrochloric acid (HCl) without the addition of an oxidizing agent. While the standard redox potential of Cu²⁺ is typically considered too low for silicon oxidation in HF, we observed anisotropic etching, yielding pyramidal and inverted pyramidal surface structures, with etching rates up to 14.18 µm h⁻¹. The presence of HCl is crucial as it prevents the significant copper film deposition seen in HCl-free solutions. Our analysis, including cyclic voltammetry and XPS, reveals that the Cu²⁺ ions act as a catalyst for silicon oxidation by dissolved oxygen, O₂. The HCl stabilizes the reduced species, Cu⁺, as chloro-complexes of copper(I), maintaining the copper in solution and enabling a divalent dissolution mechanism. This work demonstrates a unique MACE regime where the metal catalyst remains dissolved, providing new insights into the complex mechanisms of silicon dissolution.

The Front Cover shows a cobalt tetraphenylporphyrinate-chitosan-based microsphere excited by a 930 nm pulsed laser. This excitation induces an intense second harmonic generation (SHG)emission,aswellasdynamic and magnetic properties in the microsphere. The chitosan coating allows for the biocompatibility of the nanospheres for applications such as SHG biosensors and in dynamic and magnetic anticancer therapies. More information can be found in the Research Article by D. Marabello and co-workers (DOI: 10.1002/ejic.202500452).

The synthesis of dinuclear model complexes is important for developing new cooperative catalytic systems. Therefore, a series of dinuclear copper complexes, [Cu₂(OCOR)₂([18]ane-N₆)][PF₆]₂ (R = CF₃, ^tBu, Ph), featuring two copper metal centers encapsulated within a 1,4,7,10,13,16-hexaazacyclooctadecane (1) macrocycle, were synthesized by reacting ligand 1 with the corresponding Cu(II) salts, Cu(OCOR)₂. The molecular structures of these complexes were elucidated through experimental and theoretical methods. In addition, their potential application in the electrochemical reduction of CO₂ was preliminarily investigated.

Abnormal N-heterocyclic carbenes (aNHCs) have recently attracted significant attention as ligands in transition-metal catalysis due to their stronger σ-donating ability compared to normal NHCs (nNHCs). In this study, we employ density functional theory to explore the bonding characteristics and electronic properties of palladium complexes containing both nNHC and aNHC ligands. The analysis focuses on the nature of the PdC_carbene interaction, evaluating bond strength, charge distribution, and orbital contributions. Frontier orbital analysis reveals that the highest occupied molecular orbital in aNHCs corresponds to a destabilized σ-lone pair on the carbene carbon, which enhances their donor capacity relative to nNHCs. Natural bond orbital (NBO) and bond dissociation energy calculations confirm that aNHC ligands transfer electron density more effectively, resulting in shorter and stronger PdC bonds. At the same time, reduced π-backbonding is observed in aNHC complexes, consistent with their weaker π-acceptor character. Quantum theory of atoms in molecules and energy decomposition analysis further demonstrate that the PdC_carbene bonds possess mixed ionic–covalent character, with electrostatics dominating the interaction. Collectively, these results explain the greater reactivity and catalytic efficiency of aNHCPd complexes and provide guiding principles for the design of next-generation carbene ligands in organometallic catalysis.

The Front Cover shows a family photo gallery illustrating the components of a new class of porous porphyrin nanotubes (PNTs). A series of nanotubes incorporating a range of dicationic metal centres and carboxylate ligands has been synthesised. All nanotubes within the family assemble as isostructural crystals with an approximately hexagonal cross-section, offering the scope for structural tailoring to meet desired functional requirements. More information can be found in the Research Article by J. M. White and co-workers (DOI: 10.1002/ejic.202500493).

Herein, we report two novel boron complexes of the type [(L)B(OC₆H₄O)] synthesized from an o-hydroxyaryl ketimines Schiff bases viz. (E)-2-(1-(p-tolylimino)ethyl)phenol (HL¹)/(E)-2-(1-(o-tolylimino)ethyl)phenol (HL²), and 2-isopropoxy-1,3,2-benzodioxoborole [(PrⁱO)B(OC₆H₄O)] in benzene. The Schiff bases and boron complexes were characterized by elemental analyses, FT-IR, NMR, and HRMS studies. The spectral and X-ray analysis reveal that boron complexes are tetra-coordinated through O, O- atoms of the 1,2-dihydroxybenzene moiety and N,O- atoms of Schiff bases and they adopt a distorted tetrahedral geometry around boron atom. The DNA cleavage activities of Schiff bases and their boron complexes were assessed using agarose gel electrophoresis method. Our findings reveal that both the parent Schiff bases and their corresponding boron complexes exhibit significant DNA cleavage potency.

Biomass-derived muconic acid (MA) is a promising platform molecule for the sustainable production of a range of value-added chemicals, including adipic acid (AdA), hexenedioic acids, and muconolactone (Mlac). AdA is a key precursor in the synthesis of nylon 6,6. A renewable route to AdA via MA hydrogenation offers a greener alternative, aligning with the goals of circular and carbon-neutral chemical manufacturing. In this work, we explore the selective hydrogenation of MA over Pd_xCu_y/TiO₂ catalysts, focusing on the tunable production of three distinct compounds of industrial relevance. Pd-rich catalysts exhibit high activity and selectivity toward full hydrogenation to AdA. With increasing Cu content, a shift in selectivity is observed, favoring the formation of 2- and 3-hexenedioic acids, which are of interest for modifying polymer properties. At high Cu loading, the reaction pathway leads predominantly to Mlac, a versatile intermediate for fine chemical synthesis. Catalyst structure–function relationships were investigated using transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy, revealing that the nature and distribution of Cu relative to Pd significantly influence the reaction selectivity. These findings demonstrate the potential of catalyst engineering to steer biomass-derived feedstocks toward multiple high-value chemical products, offering a flexible and sustainable platform for green chemical synthesis.

In seminal work on the oxidation of Pt^II(acac)₂ to trans-Pt^IV(acac)₂I₂ (acac = [acetylacetonato-O,O′]⁻) by diiodine, Hopgood and coworkers proposed that coordination of diiodine to platinum(II) occurs forming a complex Pt^II(acac)₂(η¹-I₂) with a linear “Pt-I–I” motif and that this complex reacts with I^• via a free-radical chain reaction following photochemical initiation of I^• from uncoordinated diiodine (Hopgood et al. 1973). We report a computational study of this fundamental mechanistic proposal, finding support for the kinetic evidence. The iodine doublet interacts initially with the π-system of an acac group via the central γ-carbon atom, [(I···acac)Pt(acac)(η¹-I₂)]^•, followed by migration to the platinum center leading to formation of an intermediate trans-[IPt(acac)₂I···I]^• in which the “Pt-I···I” group is bent (104.2°), and the peripheral iodine atom is weakly interacting (I···I 3.395 Å). Subsequent migration of I^• to the other acac ligand leads to formation of a C_γ···I interaction in trans-[Pt(acac)(acac···I)I₂]^• and finally departure to continue propagation releasing the end-product trans-Pt^IV(acac)₂I₂. The reverse reaction occurs by photochemical initiation of I^• allowing access to trans-[Pt(acac)(acac···I)I₂]^•. Both the oxidation and the reverse reaction compute as low energy processes, ΔG^† ca. 7 and ca. 10 kcal mol⁻¹, respectively, consistent with rapid reactions observed experimentally.

The Front Cover highlights the synthesis, characterization and photophysics of tetra-cationic porphyrins containing peripheral tricarbonyl-Re^I complexes in interaction with bio-macromolecules such as bovine serum albumin (BSA). More information can be found in the Research Article by B. A. Iglesias and co-workers (DOI: 10.1002/ejic.202500530).

The reaction of difluoro(mesityl)borane (1), as its adduct with 4-(dimethylamino)pyridine (dmap), with (naphthalen-1,8-diyl)dilithium results in the formation of the aryl-substituted naphtho[1,8-bc]borete (3)—the boron-containing analogue of an elusive cyclobuta[de]naphthalenium cation—as a dmap adduct (3·dmap). This trapped borete, as well as 1·dmap and the analogous adducts of 1 with pyridine (py) and 3,5-lutidine (lut) have been fully characterised by multinuclear NMR spectroscopy and X-ray crystallography using Hirshfeld atom refinement with custom-generated aspherical atomic scattering factors. Free borete 3 is transient in the absence of dmap, and density-functional theory calculations support a rapid dimerisation to the corresponding 1,5-borocine (2) via (4 + 4) cycloaddition, i.e., σ-bond metathesis. While the 3·dmap adduct proved highly kinetically stable, the release and dimerisation of 3 was observed under mass-spectrometric conditions.