Ligand-enforced geometric constraints and associated reactivity in p-block compounds

Chemical Society Reviews, Journal Year: 2023, Volume and Issue: 53(2), P. 764 - 792

Published: Dec. 15, 2023

This review presents a group-wise summary of ligand enforced non-VSEPR geometries in compounds the p-block elements and discusses emergent consequences for reactivity.

Language: Английский

---

Exploring the Use of “Honorary Transition Metals” To Push the Boundaries of Planar Hypercoordinate Alkaline-Earth Metals

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(24), P. 16689 - 16697

Published: June 6, 2024

The quest for planar hypercoordinate atoms (phA) beyond six has predominantly focused on transition metals, with dodecacoordination being the highest reported thus far. Extending this bonding scenario to main-group elements, which typically lack d orbitals despite their larger atomic radius, posed significant challenges. Intrigued by potentiality of covalent formation using heavier alkaline-earth metals (Ae = Ca, Sr, Ba), so-called "honorary metals", we aim push boundaries hypercoordination. By including rings formed 12–15 boron–carbon and Ae centers, propose a design scheme 180 candidates phA. Further systematic screening, structural examination, stability assessments identified 10 potential clusters metal (phAe) as lowest-energy form. These unconventional structures embody dodeca-, trideca-, tetradeca-, pentadecacoordinate atoms. Chemical analyses reveal important role in facilitating interactions between central atom surrounding rings, thereby establishing new record coordination numbers two-dimensional realm.

Language: Английский

---

Calcium‐Ligand Cooperation Promoted Activation of N₂O, Amine, and H₂ as well as Catalytic Hydrogenation of Imines, Quinoline, and Alkenes

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(21)

Published: March 27, 2024

Abstract Bond activation and catalysis using s‐block metals are of great significance. Herein, a series calcium pincer complexes with deprotonated side arms have been prepared pyridine‐based PNP PNN ligands. The were characterized by NMR X‐ray crystal diffraction. Utilizing the obtained complexes, unprecedented N 2 O metal‐ligand cooperation (MLC) involving dearomatization‐aromatization pyridine ligand was achieved, generating aromatized diazotate as products. Additionally, dearomatized able to activate N−H bond well reversibly H , offering an opportunity for catalytic hydrogenation various unsaturated molecules. DFT calculations applied analyze electronic structures synthesized explore possible reaction mechanisms. This study is important complement area MLC main‐group metal chemistry.

Language: Английский

---

Why Are Some Pnictogen(III) Pincer Complexes Planar and Others Pyramidal?

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(57)

Published: July 30, 2024

Geometrically-constrained pnictogen pincer complexes have emerged in recent years as platforms for unique stoichiometric and catalytic chemical transformations. These feature dynamic conformations ranging from fully planar at the centre to distorted-pyramidal geometries, well variation between phases. Although valued reactivity of is ascribed their there no unified model explain observed conformational outcomes across different ligands centres. Here we propose such a through computational analysis more than 1300 structures 64 (16 4 heavy pnictogens), explaining experimental observations making new predictions. By looking signatures bond stability (bond lengths, Wiberg indices) delocalization (NPA charges, Hirshfeld charges), our framework posits pnictogen-based σ-bonding effect that favours pyramidalization exists competition with ligand-based π-bonding planarity. Variations structure function identity, ligand tethering, electronics, aromaticity can be reconciled reference balance these two opposing forces. Careful consideration σ/π-bonding effects may aid rational design future predictable geometries reactivities.

Language: Английский

---

Diverse Functionality of Molecular Germanium: Emerging Opportunities as Catalysts

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(35), P. 24209 - 24232

Published: Aug. 22, 2024

Fundamental research on germanium as the central element in compounds for bond activation chemistry and catalysis has achieved significant feats over last two decades. Designing strategies small molecule activations ultimate catalysts established capitalize orbital modalities of germanium, apparently imitating transition-metal frontier orbitals. There is a growing body examples contemporary implicating tunability orbitals through avant-garde approaches such geometric constrained empowered reactivity, bimetallic complementarity, cooperative etc. The goal this Perspective to provide readers with an overview emerging opportunities field germanium-based by perceiving underlying key principles. This will help convert discrete set findings into more systematic vision catalyst designs. Critical exposition germanium's participations evokes challenges involved innovative designs, wherein viewpoints are provided. We close addressing forward-looking directions catalytic manifold development. hope that be motivational applied constituent pragmatic catalysts.

Language: Английский

---

Li4F4−: Planar tetracoordinate fluorine in a highly viable binary mono-anionic cluster

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(16)

Published: April 22, 2025

Planar hypercoordinate fluorine is elusive due to the high electronegativity of fluorine, which restricts electron delocalization. Despite some progress, planar tetracoordinate (ptF) anionic species with simple components suitable for photoelectron spectroscopy have not yet been reported. Herein, we introduce first binary mono-anionic Li4F4− cluster containing a ptF center C2v symmetry. At given level theory, it global minimum (GM) structure good dynamic stability and significant barriers interconversion into lowest energy isomers. It noteworthy that GM neutral Li4F4 adopts cube configuration similar typical bulk lithium fluoride crystal rather than shape. The dominated by electrostatic interactions, supplemented weak covalent component any aromaticity. highly viable promising candidate experimental detection characterization.

Language: Английский

---

CBe₂H₅⁻: Unprecedented 2σ/2π Double Aromaticity and Dynamic Structural Fluxionality in a Planar Tetracoordinate Carbon Cluster

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(15)

Published: Jan. 11, 2024

Abstract A 14‐electron ternary anionic CBe 2 H 5 − cluster containing a planar tetracoordinate carbon (ptC) atom is designed herein. Remarkably, it can be stabilized by only two beryllium atoms with both π‐acceptor/σ‐donor properties and hydrogen atoms, which means that the conversion from methane (transition state) to ptC species (global minimum) requires substitution of atoms. Moreover, ligand exhibit alternate rotation, giving rise interesting dynamic fluxionality in this cluster. The electronic structure analysis reveals flexible bonding positions due C−H localized bonds, highlighting rotational cluster, 3c–2e delocalized bonds endow its rare 2σ/2π double aromaticity. Unprecedentedly, fluxional process exhibits type (σ bond↔π bond), an uncommon mechanism. seen as attempt apply hypercoordinate molecular motors.

Language: Английский

---

Alkali-Noble Metal Synergy in F©Li₄M₄^– (M = Ag, Au): A Novel Ionic Framework for Stabilizing Planar Tetracoordinate Fluorine

The Journal of Physical Chemistry A, Journal Year: 2025, Volume and Issue: unknown

Published: May 9, 2025

Planar tetracoordinate fluorine (ptF) has long been considered elusive due to the high electronegativity and lone-pair rigidity of fluorine. Herein, we report star-like ptF clusters in noble metal-bridged F©Li4M4- (M = Ag, Au) via a purely ionic mechanism. Combining density functional theory (DFT) coupled-cluster calculations, these D4h-symmetric global minima feature central F- electrostatically confined by Li4 square with Ag/Au bridges optimizing cavity size. Natural bond orbital analysis shows that there is substantial charge transfer between F Li, while covalency almost negligible. Born-Oppenheimer molecular dynamics simulations reveal their excellent dynamic stability at room temperature. The vertical detachment energies (3.62 5.07 eV) classify them as superhalogen anions. Notably, not reliant on aromaticity; rather, it primarily governed electrostatic interactions. This work expands field chemistry highlights role metals geometric enablers for hypercoordination.

Language: Английский

---

Concatenating Structural Constraint Effects at Tin for the Sequential Generation, Stabilization, and Transfer of Acyclic Aminocarbenes

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: unknown

Published: April 11, 2024

Structural constraint approaches have been employed toward different ends in recent years, from augmenting the nucleophilicity pyramidalized low-valent p-block compounds to enhancing Lewis acidities at planarized tetravalent elements. While previous studies exploited these effects separately, this work introduces a strategy concatenate structural individual stages of reaction sequence row unlock synthetic path unattainable by conventional methodologies. The boosted resulting constrained tetracoordinated calix[4]pyrrolato stannate(II) dianion enables reductive formation sterically unprotected acyclic aminocarbenes. These amino carbenes are stabilized concomitantly formed square-planar stannane(IV) as air-stable adducts. Transfer onto copper(I) cooperativity calix[4]pyrrole ligand finalizes protocol hitherto unreported yet prototypical carbene complexes. Detailed spectroscopic and quantum theoretical analyses establish synergy constraints element–ligand cooperation linchpin its selectivity.

Language: Английский

---

Tetra-Amido Macrocyclic Ligand (TAML) at Silicon(IV): A Structurally Constrained, Water-Soluble Silicon Lewis Superacid

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(37), P. 25727 - 25737

Published: Sept. 3, 2024

Tetracoordinate silicon species are typically tetrahedral, weak Lewis acids, and often sensitive to moisture. In this study, we present a tetra-amido macrocyclic ligand (TAML)-substituted Si(IV), isolated as its bis(pyridine) adduct. Due structural constraint toward anti van't-Hof/Le Bel geometry, compound exhibits superacidity effectively catalyzes the hydroboration of pyridine. Kinetic computational analyses catalytic cycle reveal that TAML-Si(IV) acts hydride transfer agent, hydrido silicate key intermediate is isolated. Notably, acid highly soluble (5 g/L) long-term stable in water. Unlike previously described silicon-H

Language: Английский

---