Over the last two decades the field of metallosupramolecular self-assembly has emerged as a promising research area for the development of intricate, three-dimensional structures of increasing complexity and functionality. The advent of this area of research has strongly benefited from design principles that considered the ligand geometry and metal coordination geometry, thus opening up routes towards rationally designed classical (Archimedean or Platonic) architectures. In this tutorial review, we will focus on more recent developments in the design and synthesis of three-dimensional suprastructures which have non-classical architectures (non-Archimedean/Platonic solids) and we will explicitly address the secondary effects responsible for their formation. Three classes of metallosupramolecular assemblies will be discussed: architectures formed through the combination of a single ligand and metal, heteroleptic structures and heterometallic structures. It is hoped that our exposition may suggest how different principles employed in these three classes of structures might be combined to create even greater complexity and potential for function.

Building on architectural principles for three-dimensional metallosupramolecular construction

Since the discovery of the first stable N-heterocyclic carbene (NHC) in the beginning of the 1990s, these divalent carbon species have become a common and available class of compounds, which have found numerous applications in academic and industrial research. Their important role as two-electron donor ligands, especially in transition metal chemistry and catalysis, is difficult to overestimate. In the past decade, there has been tremendous research attention given to the chemistry of low-coordinate main group element compounds. Significant progress has been achieved in stabilization and isolation of such species as Lewis acid/base adducts with highly tunable NHC ligands. This has allowed investigation of numerous novel types of compounds with unique electronic structures and opened new opportunities in the rational design of novel organic catalysts and materials. This Review gives a general overview of this research, basic synthetic approaches, key features of NHC–main group element adducts, and might be...

NHCs in Main Group Chemistry.

Oxidative addition and reductive elimination are key steps in a wide variety of catalytic reactions mediated by transition-metal complexes. Historically, this reactivity has been considered to be the exclusive domain of d-block elements. However, this paradigm has changed in recent years with the demonstration of transition-metal-like reactivity by main-group compounds. This Review highlights the substantial progress achieved in the past decade for the activation of robust single bonds by main-group compounds and the more recently realized activation of multiple bonds by these elements. We also discuss the significant discovery of reversible activation of single bonds and distinct examples of reductive elimination at main-group element centers. The review consists of three major parts, starting with oxidative addition of single bonds, proceeding to cleavage of multiple bonds, and culminated by the discussion of reversible bond activation and reductive elimination. Within each subsection, the discussion is...

Oxidative Addition and Reductive Elimination at Main-Group Element Centers

Imidazolium ionic liquids (ILs), imidazolylidene N-heterocyclic carbenes (NHCs), and zeolitic imidazolate frameworks (ZIFs) are imidazolate motifs which have been extensively investigated for CO2 adsorption and conversion applications. Summarized in this minireview is the recent progress in the capture, activation, and photochemical reduction of CO2 with these three imidazolate building blocks, from homogeneous molecular entities (ILs and NHCs) to heterogeneous crystalline scaffolds (ZIFs). The developments and existing shortcomings of the imidazolate motifs for their use in CO2 utilizations is assessed, with more of focus on CO2 photoredox catalysis. The opportunities and challenges of imidazolate scaffolds for future advancement of CO2 photochemical conversion for artificial photosynthesis are discussed.

Imidazolium Ionic Liquids, Imidazolylidene Heterocyclic Carbenes, and Zeolitic Imidazolate Frameworks for CO2 Capture and Photochemical Reduction.

https://hal.archives-ouvertes.fr/hal-01187790/document

Reductive functionalization of CO2 with amines: an entry to formamide, formamidine and methylamine derivatives

Tris- and tetrakis(imidazolium) salts react with Ag2O to give cylindrical polynuclear silver(I) complexes such as the tetrasilver derivative [Ag4(1)2](PF6)4. The silver(I) complexes undergo transmetalation with [AuCl(SMe2)] to yield homonuclear gold(I) complexes with retention of the metallosupramolecular assembly.

Self-assembly of molecular cylinders from polycarbene ligands and Ag(I) or Au(I).

Supramolecular Structures from Polycarbene Ligands and Transition Metal Ions

Vinylidene, (H2C=C), is a short-lived structural isomer of acetylene. By employing bulky and strongly electron-donating boryl co-ligands, the synthesis of an analogous group 14 vinylidene compound is reported. The digermavinylidene, {(HCDippN)2B}2GeGe, (where Dipp = 2,6-iPr2C6H3), is synthesized via oxidation of the corresponding symmetrical Ge0 compound K2[(boryl)GeGe(boryl)].

/pdf/a-stable-heavier-group-14-analogue-of-vinylidene-21s0ixqvtt.pdf

A stable heavier group 14 analogue of vinylidene

Polynuclear Architectures with Di- and Tricarbene Ligands

The trinuclear cationic zinc hydride cluster [(IMes)3Zn3H4(THF)](BPh4)2 (1) was obtained either by protonation of the neutral zinc dihydride [(IMes)ZnH2]2 with a Bronsted acid or by addition of the putative zinc dication [(IMes)Zn(THF)]2+. A triply bridged thiophenolato complex 2 was formed upon oxidation of 1 with PhSSPh. Protonolysis of 1 by methanol or water gave the corresponding trinuclear dicationic derivatives. At ambient temperature, 1 catalyzed the hydrosilylation of aldehydes, ketones, and nitriles. Carbon dioxide was also hydrosilylated under forcing conditions when using (EtO)3SiH, giving silylformate as the main product.

Arnab Rit

Papers

Self-assembly of molecular cylinders from polycarbene ligands and Ag(I) or Au(I).

Supramolecular Structures from Polycarbene Ligands and Transition Metal Ions

A stable heavier group 14 analogue of vinylidene

Polynuclear Architectures with Di- and Tricarbene Ligands

A cationic zinc hydride cluster stabilized by an N-heterocyclic carbene: synthesis, reactivity, and hydrosilylation catalysis.