Metal‐ligand cooperativity (MLC) had a tremendous impact on d‐block metal‐mediated bond activation and homogeneous catalysis. Is this concept translatable to the elements of the p‐block? Are there analogies already at hand? In this review, we describe contributions in which a p‐block element (group 13–15) and its ligand (surrounding molecular framework) operate synergistically in a substrate activation or a catalytic cycle. This activity is termed element‐ligand cooperativity (ELC), in correspondence to MLC. After the concepts of p‐block low‐valent states and frustrated Lewis pairs mimicking the ambiphilic reactivity of transition metals, the spatial proximity of nucleophilic and electrophilic reaction sites and a small HOMO‐LUMO gap in a p‐block ELC complex might offer yet another approach. Selected examples shall illustrate common reactivities of ELC, disclose conceptual analogies with d‐block MLC, and outline shortcomings in this field.

Metal‐ligand cooperativity (MLC) had a remarkable impact on transition metal chemistry and catalysis. By use of the calix[4]pyrrolato aluminate, [1]−, which features a square‐planar AlIII, we transfer this concept into the p‐block and fully elucidate its mechanisms by experiment and theory. Complementary to transition metal‐based MLC (aromatization upon substrate binding), substrate binding in [1]− occurs by dearomatization of the ligand. The aluminate trapps carbonyls by the formation of C−C and Al−O bonds, but the products maintain full reversibility and outstanding dynamic exchange rates. Remarkably, the C−C bonds can be formed or cleaved by the addition or removal of lithium cations, permitting unprecedented control over the system's constitutional state. Moreover, the metal‐ligand cooperative substrate interaction allows to twist the kinetics of catalytic hydroboration reactions in a unique sense. Ultimately, this work describes the evolution of an anti‐van't Hoff/Le Bel species from their being as a structural curiosity to their application as a reagent and catalyst.

Forcing a priori tetracoordinate atoms into planar configuration represents a promising concept for enhanced reactivity of p-block element-based systems. Herein, the synthesis, characterization, and reactivity of calix[4]pyrrolato gallates, constituting square...

Most p-block metal amides irreversibly react to metal alkoxides when subjected to alcohols, rendering reversible transformations with OH-substrates a challenging task. Herein, we describe how the combination of a Lewis...

The present work describes the reaction of triplet dioxygen with the porphyrinogenic calix[4]pyrrolato aluminates to alkylperoxido aluminates in high selectivity.M ulticonfigurational quantum chemical computations disclose the mechanism for this spin-forbidden process.Despite anegligible spin-orbit coupling constant, the intersystem crossing (ISC) is facilitated by singlet and triplet state degeneracy and spinvibronic coupling. The formed peroxides are stable toward external substrates but undergo an unprecedented oxidative pyrrole a-cleavage by ligand aromatization/dearomatizationinitiated O À O s-bond scission. Ad etailed comparison of the calix[4]pyrrolato aluminates with dioxygen-related enzymology provides insights into the ISC of metal-or cofactor-free enzymes.I ts ubstantiates the importance of structural constraint and element-ligand cooperativity for the functions of aerobic life.