Metallomimetic Chemistry of Boron

Abstract

The study of main-group molecules that behave and react similarly to transition metal (TM) complexes has attracted significant interest in the recent decades. Most notably, the attractive idea of eliminating the all-too-often rare and costly metals from catalysis has motivated efforts to develop main-group-element-mediated reactions. Main-group elements, however, lack the electronic flexibility of many TM complexes that arise from combinations of empty and filled d-orbitals and that seem ideally suited to bind and activate many substrates. In this Review, we look at boron, an element which, despite its non-metal nature, low atomic weight, and relative redox staticity has achieved great milestones in terms of TM-like reactivity. We show how in inter-element cooperative systems, diboron molecules and hypovalent complexes, the fifth element can acquire a truly metallomimetic character. As we discuss, this character is particularly strikingly demonstrated by the reactivity of boron-based molecules with H2, CO, alkynes, alkenes and even with N2.

Synthesis and Reactivity of Cationic Boron Complexes Distorted by Pyridine‐based Pincer Ligands: Isolation of a Photochemical Hofmann–Martius‐type Intermediate

“…The synthesis and study of three-coordinate boron-containing compounds has led to the development of small molecule activators, [1] reagents, [2] catalysts, [3] sensors, [4] and optoelectronic devices. [5] These and other applications can be extended through discoveries of new reactivity enabled by ligand design (Figure 1).…”

Two Push–Pull Channels Enhance the Dinitrogen Activation by Borylene Compounds

“…Of particular promise are boron-based molecules, which can activate small molecules and cleave stable covalentb onds. [3] Maier et al [4] synthesized the N 2 adducto fb orabenzene and Jin et al [5] observed B 3 (N 2 ) 3 + in the gas phase, which is stabilized throughd ative bondsb yN 2 .S imilarN 2 fixation to unstable borylenes under matrixc onditions was also detected by Edel et al [6] In all these instances, N 2 is coordinated in the terminal end-on mode with an early linear BÀNÀNa lignment.…”

“…However, owing to the scarcity, high cost, toxicity, and environmental issues associated with transition metals, main‐group metallomimetics has been regarded as an attractive alternative. Of particular promise are boron‐based molecules, which can activate small molecules and cleave stable covalent bonds . Maier et al .…”

“…Légaré et al. recognized the participation of up to two orthogonal d orbitals of a transition metal with the antibonding orbitals of N 2 critical to the linear geometry, yet there is only one symmetry‐compatible π orbital in [(CAAC)DurB] 2 N 2 . Ruddy et al.…”

Heterodiatomare Mehrfachbindung zwischen Elementen der Gruppe 13: Ein Komplex mit B‐Al‐π‐Bindung reduziert CO2

“…[55,56] Neueste Arbeiten der Arbeitsgruppen Bertrand und Stephan sowie aus unserer Arbeitsgruppe demonstrierten den Singulettcharakter von Borylenen, die durch cyclische (Alkyl)-(amino)carbene stabilisiert sind. [55,56] Neueste Arbeiten der Arbeitsgruppen Bertrand und Stephan sowie aus unserer Arbeitsgruppe demonstrierten den Singulettcharakter von Borylenen, die durch cyclische (Alkyl)-(amino)carbene stabilisiert sind.…”