Category Archives: European Journal of Inorganic Chemistry

Synthesis, Structure, and Catalytic Activity of Cyclometalated Iridium Complexes with a Bidentate POC Ligand

Posted on 11 September 2023 by nAlexey V. Polukeevn

Synthesis and characterization of cyclometalated iridium complexes (POC)(L)IrHCl with a bidentate POC ligand is presented. The catalytic activity of complexes (POC)(L)IrHCl in acceptorless dehydrogenation of 1-phenylethanol and transfer dehydrogenation of ethanol is discussed and compared to (POCOP)IrHCl and (PCN)IrHCl pincer complexes.

Abstract

Synthesis, characterization and catalytic activity of cyclometalated iridium complexes with a bidentate POC ligand is presented. Metalation of POC-H (di-tert-butyl(phenoxy)phosphane) with [Ir(COD)Cl]₂ proceeded rapidly at room temperature and afforded mixture of (POC)(POC-H)IrHCl (1 a) and (POC)(COD)IrHCl (1 b), from which complexes (POC)(L)IrHCl where L=PPh₃ (1 c), bipyridine (1 d) and [2,2′-bipyridine]-6,6′-diol (1 e) were prepared through ligand exchange. The compounds were tested in acceptorless dehydrogenation of 1-phenylethanol and transfer dehydrogenation of ethanol in a context of comparison with pincer counterparts (POCOP)IrHCl and (PCN)IrHCl. An attempt to prepare a dihydride complex from 1 e led to dimeric complex [(POC)(bipy-diol−)IrH]₂ (3) that could explain the low activity of 1 e. DFT studies provided insight into POC-H vs POCOP-H metalation mechanism.

Get under the Umbrella: A Comprehensive Gateway for Researchers on Lanthanide‐Based Single‐Molecule Magnets

Posted on 11 September 2023 by nKevin Bernotn

In order to help young researchers in Molecular Magnetism, this article proposes a “review of reviews” also known as an “umbrella review” on lanthanide-based monomolecular magnets (4 f-SMM). Bibliographic search techniques are commented together with AI-based tools for bibliographic search, indexing, and summarization. Milestones in 4 f-SMM are identified. Books, book articles, and reviews are contextualized. This article is therefore proposed as a gateway to the 4 f-SMM field.

Abstract

The number of scientific articles that need to be considered to cover a research topic is ever-increasing and quite difficult for a newcomer to assimilate. This is particularly true in dynamic discipline like Molecular Magnetism. In order to help young researchers in this field, this article proposes a “review of reviews” also known as an “umbrella review” on lanthanide-based single-molecule magnets (4 f-SMM). As a preamble, various bibliographic search techniques and AI-based tools for bibliographic search, indexing, and summarization are proposed and commented. Then, the main milestones in 4 f-SMM are identified. In the core of the paper, books, book articles, and reviews dealing with 4 f-SMM are contextualized and classified by subtopics. This article is therefore proposed as a gateway to the 4 f-SMM field.

Trapping an Unexpected/Unprecedented Hexanuclear Ce(III) Hydrolysis Product with Neutral 4‐Amino‐1,2,4‐triazole

Posted on 11 September 2023 by

We describe a straightforward pathway to obtain lanthanide hydroxo polynuclear clusters from lanthanide salt hydrates and a combination of azoles. 4-NH₂-1,2,4-triazole was found to play an important role both as a reaction medium and the structure-forming agent leading to multiple clusters with various nuclearity including the first example of a high nuclearity lanthanide complex where all Ln atoms are pairwise connected through 12 N-donor ligands.

Abstract

Using Ce(III) as both a representative lanthanide and actinide analog, the ability of mixtures of acidic and basic azoles to allow direct access to homoleptic N-donor f-element complexes in one pot reactions from hydrated salts as starting materials was examined by reacting mixtures of 4-amino-1,2,4-triazole (4-NH₂-1,2,4-Triaz), 5-amino-tetrazole (5-NH₂-HTetaz), and 1,2,3-triazole (1,2,3-HTriaz) in 1 : 1 and 1 : 3 ratios with CeCl₃ ⋅ 7H₂O, [C₂mim]₃[CeCl₆] ([C₂mim]⁺=1-ethyl-2-methylimidazolium), and Ce(NO₃)₃ ⋅ 6H₂O. Although unsuccessful in our goal, structural analysis revealed that neutral 4-NH₂-1,2,4-Triaz is structure directing via η ² μ ₂ κ ² bridging, with the formation of the dinuclear complexes [Ce₂Cl₂(μ₂-4-NH₂-1,2,4-Triaz)₄(H₂O)₈]Cl₄ ⋅ 4H₂O, [Ce₂(μ₂-4-NH₂-1,2,4-Triaz)₄(4-NH₂-1,2,4-Triaz)₂(Cl)₆], and [4-NH₂-1,2,4-HTriaz][Ce₂(μ₂-4-NH₂-1,2,4-Triaz)₂(μ₂-NO₃)(NO₃)₆(H₂O)₂]. When the synthetic conditions favored hydrolysis, the hexanuclear Ce(III) complex [Ce₆(μ₃-O)₄(μ₃-OH)₂(μ₃-Cl)₂(Cl)₆(μ₂-4-NH₂-1,2,4-Triaz)₁₂] ⋅ 7H₂O was isolated. This unexpected hydrolysis product represents the first example of a high nuclearity lanthanide complex where all Ln atoms are pairwise connected through 12 N-donor ligands or 12 neutral bridging ligands of any type, a rare example of incorporation of non-oxo coordinating anions in the M₆X₈ core, and the first reported Ce(III) hexanuclear complex of this type.

Exploring LiZnNbO4 as a Host for New Colored Compounds: Synthesis, Structure, and Material Properties of NbZn1‐x Mx LiO4 (M=Mn, Co, Ni, Fe) and Nb1‐ySby Zn1‐x Mx LiO4 (M=Co, Ni)

Posted on 11 September 2023 by nDiksha Malik, nSrinivasan Natarajann

Transition elements (Co²⁺, Ni²⁺, and Cu²⁺ ions) were substituted in place of tetrahedral Zn²⁺ ions in the tetragonal non-centrosymmetric spinel LiZnNbO₄ (LZN) and LiZnNb_0.5Sb_0.5O₄ (LZSN) compounds to form new colored compounds. The dielectric studies indicated reasonable values with low loss. The compounds were SHG-active. Magnetic studies reveal the Co²⁺ substituted Li(Zn_0.25Co_0.75)NbO₄ compound to be antiferromagnetic in nature.

Abstract

The non - centrosymmetric tetragonal inverse spinel structure of LiZnNbO₄ has been explored with a view to prepare new colored compounds. The substitution of Co²⁺, Ni²⁺, Fe²⁺, Mn²⁺, and Cu²⁺ ions were attempted in the place of Zn²⁺ ions and Sb⁵⁺ ions in place of Nb⁵⁺ ions. The studies indicated that 0.75 Zn²⁺ ions in LiZnNbO₄ can be replaced by Co²⁺ ions and 0.5 Zn²⁺ ions in LiZnNb_0.5Sb_0.5O₄ compound. The substitution of Co²⁺ ions gives rise to different shades of blue color in Li(Zn_1-xCo_x)NbO₄ compounds and from ink blue to blue-green color in Li(Zn_1-xCo_x)(Nb_0.5Sb_0.5)O₄ compounds. The different colors observed in the present study were explained by the traditional allowed d-d transitions as well as the metal-to-metal charge transfer (MMCT) transitions involving Nb⁵⁺ (4d ⁰) ions and partially filled 3d electrons. The SHG studies indicate that the prepared compounds are SHG active. All the compounds exhibit reasonable dielectric behavior with low loss. The XPS studies confirm the oxidation states of the different substituted ions. Raman studies indicate variations in the bands due to the substitutions in the parent LiZnNbO₄ phase. Magnetic studies on the Co²⁺ ions substituted compounds suggest antiferromagnetic behavior.

Vanadium(IV)‐oxo Corrole Catalyzed Selective Oxidative Cleavage of Alkenes to Aldehydes

Posted on 8 September 2023 by nPanisha Nayak, nManisha Nayak, nSubhajit Kar, nSanjib Karn

An oxo[5,10,15-tris(4-nitrophenyl)corrolato]vanadium (IV) complex (cat.), has been successfully synthesized and the existence of two tautomeric forms of this complex in solution has been established. Oxo[5,10,15-tris(4 nitrophenyl)corrolato]vanadium (IV) (cat.) in the presence of H₂O₂ cleaves olefinic bonds to yield the corresponding aldehyde compounds. A mechanism was also proposed for these catalysis reactions.

Abstract

A practical and efficient protocol for oxidative cleavage of olefinic bonds especially in arylated olefins has been demonstrated. Herein, an oxo[5,10,15-tris(4-nitrophenyl)corrolato]vanadium (IV) complex (cat.), has been successfully synthesized and the existence of two tautomeric forms of this complex in solution has been established. Oxo[5,10,15-tris(4-nitrophenyl)corrolato]vanadium (IV) (cat.) in the presence of H₂O₂ cleaves olefinic bonds to yield the corresponding aldehyde compounds. In general, a high valent, oxo-(porphyrinoid)-metal complex catalyzes the epoxide formation reactions, however, in the present case, we have observed the exclusive formation of aldehydes. The reaction offered aryl aldehydes with good yields and excellent selectivity. A mechanism was also proposed for these catalysis reactions.

Efficient One‐pot Zeolite Synthesis Protocol from the Metastable *BEA to MTW Topology and Its Impact on the Methanol‐to‐Hydrocarbons Process

Posted on 8 September 2023 by nYiru Ye, nXue Zhou, nXin Zhang, nAbhishek Dutta Chowdhuryn

The “one-pot” inter-zeolite conversion process has been probed during the transformation from *BEA to MTW topology, which was subjected to methanol-to-hydrocarbons reactions and advanced characterization (including operando conditions) to derive structure-reactivity relationships.

Abstract

The inter-zeolite conversion is a method to convert one meta-stable zeolite to a thermodynamically stable zeolite. Despite the enormous interest, this method is yet to be popularized or standardized in the zeolite community. Intending to provide more insights into hydrothermal conversions from one zeolite to another, this work developed a novel one-pot and flexible synthetic protocol to efficiently obtain the meta-stable *BEA topology and its derived MTW topology by varying the hydrothermal crystallization time. This inter-zeolite conversion process led to changes in the zeolite framework and modified physicochemical properties during the process. Such a transformation was feasible by forming hierarchical zeolite phases sharing a similar “mtw”-based common building units, possibly driving such conversion. The structure-reactivity relationship of four different zeolite materials, synthesized from this one-pot inter-zeolite conversion method, was established concerning their performance in the methanol-to-hydrocarbon (MTH) process, which has been well supported by operando UV-vis diffuse reflectance spectroscopic study coupled with online mass spectrometry and solid-state NMR spectroscopy. As a result, the pathway to synthesize various target zeolites from an identical initial synthesis gel with desired physicochemical properties has been scrutinized.

Chiral Substitution on Spaced Cations Lead to Improved Properties and Reversible Phase Transition, Broadband Emission in Parent Compound (3APr)PbBr4

Posted on 8 September 2023 by

We report a multifunctional compound: (3APr)PbBr₄ (1) (3APr=3-Pyrrolidinamine) and corresponding enantiomer R and S-(3APr)PbBr₄ (R/S-2). Compound 1 show reversible solid-state phase transition, step-like dielectric anomaly and broadband yellow emission under ultraviolet light excitation. the R/S-2 display mirror image structural relationship, increases quantum yield and CD signal.

Abstract

Hybrid organic-inorganic perovskites (HOIP) due to their excellent optoelectronic properties and flexible structure have attracted enthusiastic interest. In particular, introducing chirality is a method to enhance compound performance. Herein, we report a multifunctional compound: (3APr)PbBr₄ (1) (3APr=3-Pyrrolidinamine) and corresponding enantiomer R and S-(3APr)PbBr₄ (R/S-2). Compound 1 show reversible solid-state phase transition, step-like dielectric anomaly and broadband yellow emission under uv light excitation. Accompany with phase transition, structure dimension transition from 2D to 1D without space group change. Through introduce chirality, the R/S-2 display mirror image 1D structural relationship, increased quantum yield from 3.43 % (1) to 13.65 % (R/S-2) and exhibits corresponding CD signals. Then combine to first-principles analysis, it was found that fluorescence is attributed to the formation of instantaneous defects during excitation, leading to the formation of self-trapped excitons (STEs). This finding will further promote the development of multifunctional compound and the study of chiral substitution enhance compound properties.

Diverse Reactivity of a Ca(I) Synthon

Posted on 7 September 2023 by

Although complexes with Ca−Ca bonds are still elusive, a complex with a bridging C₆H₆ ²⁻ dianion reacts like a Ca^I synthon. However, depending on the reagent, different modes of reactivity have been observed.

Abstract

Low-valent Mg^I complexes like (BDI)Mg−Mg(BDI) have found wide-spread application as specialty reducing agents (BDI=β-diketiminate). Also their redox reactivity was extensively investigated. In contrast, attempts to isolate similar Ca^I complexes led to reduction of the aromatic solvents or N₂. Complex (^DIPePBDI)Ca(μ ₆,μ ₆-C₆H₆)Ca(^DIPePBDI) (VIII) should be regarded a Ca^II complex with a bridging C₆H₆ ²⁻ dianion (^DIPePBDI=HC[C(Me)N-DIPeP]₂, DIPeP=2,6-C(H)Et₂-phenyl). It can react as a Ca^I synthon by releasing benzene and two electrons. Herein we describe the reactivity of VIII with benzene, biphenyl, naphthalene, anthracene, COT, Ph₃SiCl, PhSiH₃, a (BDI)AlI₂ complex, H₂, PhX (X=F, Cl, Br, I), tBuOH and tBuCH₂I. The C₆H₆ ²⁻ dianion in VIII can react as a 2e ⁻ source, a nucleophile or a Brønsted base. In some cases radical reactivity cannot be excluded. Crystal structures of (^DIPePBDI)Ca(μ ₈,μ ₈-COT)Ca(^DIPePBDI) (1) and [(^DIPePBDI)CaX ⋅ (THF)]₂ (X=F, Cl, Br, I) (2–5) are described.

Tuning the Lewis Acidity of Neutral Silanes Using Perfluorinated Aryl‐ and Alkoxy Substituents

Posted on 7 September 2023 by

A set of Lewis acids was synthesized by installing perfluorotolyl- and perfluorocresolato ligands on neutral Si(IV) atoms. Additionally, a heteroleptic silane was synthesized using perfluoropinacolato and perfluorophenyl substituents. The obtained silanes were fully characterized and a Lewis acidity assessment was conducted by the Gutmann-Beckett and Childs method.

Abstract

The emerging field of Lewis acidic silanes demonstrates the versability of molecular silicon compounds for catalytic applications. Nevertheless, when compared to the multifunctional boron Lewis acid B(C₆F₅)₃, silicon derivatives still lack in terms of reactivity. In this regard, we demonstrate the installation of perfluorotolyl groups (Tol ^F ) on neutral silicon atoms to obtain the respective tetra- and trisubstituted silanes Si(Tol ^F )₄ and HSi(Tol ^F )₃. These compounds were fully characterized including SC-XRD analysis but unexpectedly showed no significant Lewis acidity. By using strongly electron-withdrawing perfluorocresolato groups (OTol ^F ) the tetrasubstituted silane Si(OTol ^F )₄ was obtained, bearing an 8 % increased Δδ(³¹P) shift when applying the Gutmann-Beckett method, compared to literature-known Si(OPh ^F )₄. Ultimately the heteroleptic Si(Ph ^F )₂pin ^F was successfully synthesized and fully characterized including SC-XRD analysis, introducing a highly Lewis acidic silicon atom holding two silicon-carbon bonds.

Irreversible Structural Phase Transition in [(9‐triptycylammonium) ([18]crown‐6)][Ni(dmit)2]: Origin and Effects on Electrical and Magnetic Properties

Posted on 5 September 2023 by

Two salts, [(9-triptycylammonium)([18]crown-6)][Ni(dmit)₂] (1) and [(9-triptycylammonium)([15]crown-5)][Ni(dmit)₂] (2) were prepared and characterized. [Ni(dmit)₂]⁻ formed dimers in 1 but was arranged in zigzag stacks in 2. At 381 K, 1 underwent an irreversible phase transition originating from the rearrangement of [Ni(dmit)₂] dimers and therefore experienced a drastic change in magnetic and electrical properties.

Abstract

Materials exhibiting irreversible phase transitions, leading to changes in their properties, have a potential for novel application in electronic components such as a non-rewritable high-security memory. Here, we focused on the two salts, [(9-triptycylammonium)([18]crown-6)][Ni(dmit)₂] (1) and [(9-triptycylammonium)([15]crown-5)][Ni(dmit)₂] (2), which featured 2D sheet structures with alternately stacked cation and anion layers. Both salts exhibit similar cation arrangements, however, their anion arrangements differ significantly. The temperature-dependent magnetic susceptibilities of 1 and 2 were well reproduced by the alternating chain model (J _AC1/k _B=−306(8), J _AC2/k _B=−239(3) K) and the Curie-Weiss model (θ=−3.9(1) K), respectively. 1 experience a reversible phase transition around 40–60 K, causing anomalies in magnetic behavior. Moreover, an irreversible single-crystal-to-single-crystal phase transition to 1′ undergo at ~381 K, inducing a rearrangement of [Ni(dmit)₂]⁻ anions and a resistivity decrease from 6.5×10⁶ to 6.5×10² Ω cm. The susceptibility curve of 1′ was reproduced by a combination of the Curie-Weiss and dimer models (J _dimer/k _B=−407(5), θ=−26.7(5) K). The irreversible transition of 1 is the first example for such supramolecule and [Ni(dmit)₂]⁻ system to our knowledge, in opening potential new-type materials.