Metal‐organic frameworks (MOFs), a distinguished class of crystalline porous materials, are composed of metal ions or clusters interconnected by organic linkers. MOFs are associated with different promising properties like high surface area, tunable pore structure, and significant chemical functionality that make them an attractive class of heterogeneous catalysts. The modular nature of MOFs allows for design control over their active sites within the catalytic framework. Among transition metals, manganese (Mn) has received significant attention for several reasons, including the existence of multiple accessible oxidation states (Mn 2+ , Mn 3+ , and Mn 5+ ), high redox activity, modest toxicity, and low cost. These benefits allow Mn‐MOFs to mediate a suitable host of organic transformations, such as oxidation, condensation, and multicomponent coupling reactions, under mild, green, and sustainable catalytic conditions. The combined features of the tunable structure common in MOFs and the flexible redox behavior led to enhanced catalytic performance, stability, and reusability of Mn‐MOFs. This review describes the detailed catalytic applications and mechanistic aspects of Mn‐MOFs for sustainable organic transformations developed over the past 15 years.
[1.1]Ferrocenophane was prepared by the literature method along with a small amount of [1.1.1.1]ferrocenophane, which was for the first time characterized by a crystal structure analysis. Oxidation of [1.1]ferrocenophane with DDQ afforded [1.1]ferrocenophane‐1,12‐dione. Here, new results of the chemistry of this compound are reported. One electron oxidation gave the mixed valence Fe(II)/Fe(III) monocation, which was characterized by its Mößbauer spectrum. Knoevenagel condensations of [1.1]ferrocenophane‐1,12‐dione with malonodinitrile and cyanoacetic acid esters in the presence of a Lewis acid gave a number of mono‐ and di‐condensation products, all of which showed a syn conformation. While condensations with malonodinitrile afforded the mono‐ and the di‐condensation products, less symmetric substrates such as tert ‐butyl cyanoacetate gave mixtures of diastereomers. At elevated temperatures decarboxylation reactions gave cyanomethylene substituted [1.1]ferrocenophane derivatives as diastereomeric mixtures, which could chromatographically be separated. An attempted McMurry reaction of [1.1]ferrocenophane‐1,12‐dione did not result in an intramolecular coupling but in an intermolecular combination. Finally, the reduction of [1.1]ferrocenophane‐1,12‐dione with lithium tetrahydridoaluminate followed by aqueous work up gave a small yield of an intramolecular etherification product. In eight cases, the reaction products were characterized by crystal structure analyses.
The ring‐opening polymerization (ROP) of epoxides is an important industrial route to polyether polyols used in polyurethane and surfactant value chains. Double metal cyanide (DMC) catalysts provide high activity but often show an induction period and may require promoter additives. Here, we report metal oxide modified multimetal cyanide (MMC) catalysts of general formula [MxOy]n–Zn3[Co(CN)6]2 (M = Al, Ga, In), prepared by adding Group 13 alkoxides during ZnCl2/K3Co(CN)6 precipitation in tert‐butyl alcohol. XRF, STEM‐EDS, and XRD confirm incorporation and dispersion of Group 13 oxide phases on a largely amorphous DMC framework. In semi‐batch propoxylation of dipropylene glycol, normalized to cobalt loading (~10 ppm Co), the modified catalysts show much shorter activation times (≤10 min for Ga‐containing MMCs versus 55 min for unmodified Zn–Co DMC) and faster propylene oxide uptake. Kinetic analysis at comparable equivalent weight (~400 Da) shows up to 3.2‐fold higher apparent first‐order PO consumption rates for Ga‐modified MMCs. DFT/NBO analysis indicates that stronger Lewis acidity increases O—H bond polarization, supporting alcohol O–H activation as the rate‐determining step and explaining the improved activity trends.
The rapidly growing CO 2 in the atmosphere demands a highly porous material for efficient CO 2 capture. Herein, the solvothermal method is employed to synthesize the HKUST‐1 MOF, using single‐solvent systems and mixed‐solvent systems (DMF, ethanol, water, and acetonitrile) in order to understand their impact on the framework properties. The results demonstrated that modifications in the solvent system exceptionally altered the crystallite size (ranging from ∼31 to 79 nm), morphology, and textural properties while maintaining the core framework. Fascinatingly, PD has the largest surface area, measuring 1145.5 m 2 /g, with a total pore volume of 0.46 cm 3 /g. Yet, the CO 2 adsorption performance test carried out at 298 K and up to a pressure of 1 bar followed the trend: DE > EW > PD > DW > AE > PE > AW. The performance of DE has been attributed to its significant open Cu 2+ binding sites, crystallite size, and engineered pore structure that leads to the CO 2 adsorption of 3.58 mmol g −1 . Lastly, a regeneration test on the best‐performing material (DE) indicates that it can maintain up to 75% of its initial capacity, suggesting that it can be reused for at least three cycles. Ultimately, these findings suggest that solvent‐mediated synthesis impacts the overall characteristic features of the material, leading to variation in the adsorption capacity.
The development of metal nanoclusters (NCs) has attracted significant interest due to their applications in photonics, biology, electronics, and catalysis. Their ultrasmall size, tunable structures, and well‐defined structure–property correlation make them attractive tool in the field of catalysis. This review article provides a comprehensive overview of the synthesis and characterization of metal NCs, with particular emphasis on their applications in catalytic CB bond‐forming reactions, especially the hydroboration, dihydroboration, and carboboration of alkynes. Furthermore, mechanistic studies are emphasized to elucidate the reaction pathways underlying these transformations. Considering the growing advancements in this field, the insights presented in this review are expected to inspire future developments in the design of novel metal NCs for diverse organic transformations.
Fluorinated tris(pyridyl)borate with a vinyl substituent on boron was synthesized and comprehensively characterized, expanding the diversity and functional versatility of the poly(pyridyl)borate ligand family. The coordination chemistry of this ligand with copper(I) was investigated in the presence of ethylene, carbon monoxide, and triphenylphosphine ligand auxiliaries. Single‐crystal X‐ray diffraction studies revealed distinct coordination environments, with the vinyl group directly coordinating to copper in the solid‐state structures of the CO and PPh 3 complexes, while it remains free in the ethylene complex. Room‐temperature NMR spectroscopy indicated the presence of two isomers—metal‐coordinated and free vinyl species—in CDCl 3 solutions of the ethylene and carbonyl complexes. Phosphine complexes show the presence of only one isomer in CDCl 3 solution at room temperature. These results emphasize the potential of using additional functionalities on the boron of poly(pyridyl)borate ligands to adjust the electronic and structural properties of metal coordination complexes, providing useful design principles for their application. We also demonstrate the use of a user‐friendly vinyl‐boron precursor for the ligand assembly.
The 5,11‐dipyridyl 3‐pyrrolyl BODIPY building block was synthesized by coupling of 5,11‐dibromo 3‐pyrrolyl BODIPY with 4‐pyridine boronic acid under Pd(0) coupling conditions and used it for the synthesis of 3‐pyrrolyl BODIPY‐(Zn II porphyrin) 2 triad 4 and 3‐pyrrolyl BODIPY‐(Ru II porphyrin) 2 triad 5 by adopting “axial bonding strategy”. 1D and 2D NMR techniques have been used extensively to establish the molecular structures of both the triads. NMR studies indicated that the Ru(II)‐pyridine “N” bond was stronger in 3‐pyrrolyl BODIPY‐(Ru II porphyrin) 2 triad 5 compared to Zn(II)‐pyridine “N” bond in 3‐pyrrolyl BODIPY‐(Zn II porphyrin) 2 triad 4 . The absorption and electrochemical studies showed the features of both 3‐pyrrolyl BODIPY and metalloporphyrin units and steady state fluorescence studies indicated a possibility of energy transfer from donor metalloporphyrin unit to acceptor 3‐pyrrolyl BODIPY unit in 3‐pyrrolyl BODIPY‐(Zn II porphyrin) 2 in triad 4 . Furthermore, DFT studies supported the experimental observations and provided insights into the electronic structures and excited‐state properties of the triads.
In this work, we present a systematic computational investigation of the phosphine oxide reduction by using a set of phosphine oxides and silanes. While previous studies consider the substituent effect of the phosphine oxide, few theoretical studies have addressed the silane influence over the reaction. For this reason, free energy barriers for the hydrogen transfer step were calculated and analyzed using the distortion–interaction model and natural bond orbital (NBO) theory. Our analysis of R 3 SiH silanes indicated that the highly acidic silanes Cl 3 SiH and (OCN) 3 SiH readily reduce Ph 3 PO. Further analysis revealed that Ph 2 RSiH derivatives (RCl, OCN) also exhibit low activation barriers. NBO analysis showed that the presence of a small electronegative substituent directly bonded to silicon (e.g., Cl, OH) enhances donation from the oxygen lone pair, n(O), into the σ*(SiH) and σ*(SiR) orbitals. This stabilizes the interaction energy and as a result lowers the computed energy barrier. These findings provide a unified electronic framework for phosphine oxide reduction and offer practical design principles for efficient silane reagents.
Gold(I) N ‐heterocyclic carbene (Au(I)–NHC) complexes are promising anticancer agents, but their therapeutic potential is often limited by rapid deactivation by thiol‐containing biomolecules such as glutathione (GSH) and cysteine (Cys). Here, we report a ligand engineering strategy to modulate the stability and biological activity of 1,3‐disubstituted benzimidazolium‐derived Au(I) complexes. A series of Au(I) chlorido complexes bearing diverse N ‐substituents was synthesized, and the chlorido ligand was replaced with thiolate ligands, including 2‐mercaptopyrimidine and thioglucose, to improve resistance to thiol‐mediated deactivation. The complexes were characterized by NMR, HRMS, Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), and single‐crystal X‐ray diffraction. Structural and computational studies revealed linear two‐coordinate Au(I) centers with strong AuC bonding and metal‐to‐ligand charge transfer character. The complexes showed potent cytotoxicity across multiple cancer cell lines, including HT1080, Huh‐7, MCF‐7, MDA‐MB‐231, A549, HCT116, and HeLa, with better selectivity than in noncancerous HEK293T cells. Several compounds outperformed auranofin. Mechanistic studies using inhibitors of apoptosis, necroptosis, autophagy, and ferroptosis suggested that the cytotoxicity does not involve canonical regulated cell death pathways, but it is consistent with a predominantly nonapoptotic, necrotic mode of cell death.
We computationally investigate the initiation step in polyhomologation (PH) and evaluate the reaction mechanisms of multiple initiator/ylide combinations with the aim of expanding the scope of traditional PH while preserving its key advantages. All energy profiles were benchmarked against the well‐established trihexylborane/dimethylsulfoxonium methylide (Corey’s ylide) system. Our model set comprises tripropylborane, ‐alane, and ‐galane initiators paired with nitrogen‐ and phosphorus‐based methylides. The tripropylborane/trimethylammonium methylide mechanism closely corresponds to the reference pathway, and diazonium methylide in combination with tripropylborane, tripropylalane, or tripropylgalane also reproduces the characteristic features of the established PH reaction pathway, with 1,2‐migration barriers ranging from 16.9 to 24.8 kcal mol −1 . These results indicate that such initiator/ylide pairs constitute experimentally viable candidates for extending PH chemistry. Across all systems, nitrogen‐derived ylides consistently promote PH initiation more efficiently than their phosphorus analogs, primarily due to the lower strain associated with the structural deformation of the ylide fragment and the different rigidity imposed by its substituents. Together, these mechanistic trends provide a coherent picture of initiation in PH and, supported by complementary computational analyses, offer an initial framework that can guide future development of new p ‐block‐based initiator/ylide systems.
This study presents the synthesis and photochemical characterization of a novel azobenzene‐appended tripicolylamine ligand and its corresponding zinc complex. The ligand was prepared through a five‐step synthetic route and successfully metalated with zinc(II) acetate and zinc(II) triflate. Photoisomerization studies revealed that the ligand and zinc complex achieve ~85% trans‐to‐cis conversion with 370 nm irradiation while maintaining excellent reversibility across multiple switching cycles. As expected, thermal back‐isomerization kinetics follow first‐order behavior with half‐lives of 50 and 59 h for the ligand and complex, respectively. Coordination to Zn(II) preserves the photoswitching characteristics of the free ligand, providing a well‐defined model platform for studying photoresponsive coordination chemistry.
A novel Hoveyda-Grubbs' second-generation-type ruthenium complex featuring an unsymmetrical N-heterocyclic carbene (uNHC) ligand with N-cyclohexyl, N'-ortho-difluorophenyl substituents and syn phenyl groups on the backbone was synthesised and fully characterised. Its catalytic performance was evaluated in representative ring-closing metathesis (RCM), cross-metathesis (CM) and ring-opening metathesis polymerisation (ROMP) reactions and compared with that of a non-fluorinated analogue. The introduction of fluorine affects both the stability and catalytic performance of the resulting complex by modulating the steric and electronic properties of the NHC ligand. In RCM reactions, the fluorinated catalyst showed improved activity relative to the non-fluorinated counterpart, whereas in CM reactions similar activity and selectivity were observed for both catalysts. In the ROMP copolymerisation of norbornene with cis-cyclooctene, the fluorinated complex exhibited lower chemoselectivity in the formation of alternating copolymers.
The reaction of oxalyl halide isothiocyanate, X(CO)2NCS (X = Cl (1), Br (2)), with activated carbon proceed via decarbonylation to yield the corresponding carbonyl halide isothiocyanate. Both compounds were isolated as liquids at room temperature and exhibit characteristic resonances in 13C NMR as well as distinct features in their vibrational spectra. Crystal structures of carbonyl chloride isothiocyanate and carbonyl bromide isothiocyanate are reported, revealing an anti orientation of the isothiocyanate group relative to the carbonyl moiety and distinct intermolecular interactions governing the crystal packing. Furthermore, the reactivity of 1 toward O- and S-nucleophiles was investigated, leading to the formation of thiocarbamate derivatives, which were structurally and spectroscopically characterized.
Orthorhombic Mn 2 SnS 4 with defect‐ordered rock salt structure exhibits complex magnetic properties with two magnetic transitions, antiferromagnetism at around 152 K and a weak ferromagnetism at 53 K. In this article, we have studied the effect of copper(I) substitution on the structure and magnetic properties of Mn 2− x Cu x SnS 4 . A structural phase transition from orthorhombic defect‐ordered rock salt structure, Cmmm (for x = 0.05 and 0.1) to cubic spinel structure, Fd −3 m ( x = 0.6 and 0.7) is observed with Cu substitution in Mn 2− x Cu x SnS 4 . In the defect‐ordered rock salt structure, Cu goes to the octahedral Mn site, while in the spinel structure, Cu along with Mn goes to tetrahedral voids. With initial Cu(I) substitution in the orthorhombic phase, the low‐temperature weak ferromagnetic ordering temperature increases from 53 K to about ∼140 K and ∼120 K for x = 0.05 and 0.1, respectively, while the high‐temperature antiferromagnetic ordering temperature remains invariant. Higher amount of Cu substitution in Mn 2− x Cu x SnS 4 leads to structural transformation of orthorhombic to a cubic spinel phase (0.6 ≤ x ≤ 0.7), in which the magnetic ions occupy both tetrahedral and octahedral voids in a disordered manner resulting in further lowering of magnetic ordering temperature.
1,4-Diaza-1,3-dienes (DADs) are among the most widely used redox-active ligands. In this study, we examine how this redox non-innocence governs the reactivity of a DAD ligand in its enediamide dianion form, [DAD](2-), toward organic carbonyl compounds. The key question is whether the enediamide dianion acts solely as an electron donor - thus remaining a spectator ligand - or whether it assumes an active, bond-forming role. All reactions described herein employ the dilithium complex [{(THF)(2)Li}(2)(tBu-DAD)], derived from N, N '-bis(tert-butyl)-1,4-diaza-1,3-diene, as an enediamide equivalent. The reaction with aldehydes or ketones (1:1 stoichiometry) proceeds via single-electron transfer from the enediamide moiety, coupled with C-C bond formation at the carbonyl carbon, to afford trifunctional oxido amido imine products. In contrast, reaction with an ester such as ethyl acetate involves two single-electron transfer steps, resulting in an overall two-electron redox process and attachment of two enediamide units to the ester carbonyl carbon through newly formed C-C bonds. This dual role becomes more apparent in reactions with benzyl benzoate. The product reveals that both carbon atoms of the enediamide C=C unit bond to the ester carbonyl carbon accompanied by cleavage of the C=C bond and formal insertion of the carbonyl carbon into the ligand backbone.
We have synthesized the tetragonal modification of LiSr 2 H 2 N and novel LiBa 2 H 2 N in single phase bulk via solid state reaction assisted by ball milling and grown single crystals from alkali metal melts. The crystal structure was determined via powder and single crystal X‐ray diffraction. The obtained structural data reveal that LiSr 2 H 2 N crystallizes in the non‐centrosymmetric space group I 4 mm , rather than in the previously reported centrosymmetric space group I 4/ mmm , resulting in a fully ordered structural model and particularly resolving the site disorder of the nitride ion in the previously discussed structure. We also report the first synthesis and crystal growth of LiBa 2 H 2 N, which crystallizes isostructural with LiSr 2 H 2 N. We discuss structural relations with the reported centrosymmetric tetragonal model and an orthorhombic form earlier reported. Furthermore, we analyze the structure of LiBa 2 H 2 N in comparison to the subnitride LiBa 2 N.
