X‑Type Aluminyl Ligands for Transition-Metal Catalysis

• Published in: ACS catalysis Vol. 12; no. 3; pp. 1626 - 1638
• Main Authors: Hara, Naofumi, Semba, Kazuhiko, Nakao, Yoshiaki
• Format: Journal Article
• Language: English
• Published: American Chemical Society 04-02-2022
• Subjects: X-type; aluminyl ligand; transition-metal catalysis
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.1c04340

Transition-metal complexes that bear group-13 X-type metalloligands have attracted considerable interest on account of their strong σ-donicity, which can dramatically tune the reactivity of transition-metal catalysts. Among the group-13 X-type metalloligands, X-type aluminyl ligands are especially interesting due to the low electronegativity and strong Lewis acidity of the Al atom. However, transition-metal complexes that bear X-type aluminyl ligands had until recently remained elusive. In this perspective, we describe the reactivity of transition-metal complexes that carry a well-designed X-type PAlP pincer-ligand and their characteristic features, i.e., strong σ-donicity, trans-influence, reverse bond polarization, and Lewis acidity. These properties enable various catalytic transformations, including transfer dehydrogenation, highly efficient CO2 reduction, site-selective C–H-bond functionalization, and cooperative C–F- and C–O-bond functionalization, which are challenging to achieve using conventional catalyst systems.