Element‐Ligand Cooperativity with p‐Block Elements

Abstract

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.

An isolable, crystalline complex of square-planar silicon(IV)

“…It represents an unprecedented, spontaneous carbosilylation of an alkyne with high synthetic potential, and the first example of silicon-element ligand cooperativity in its classical sense. 64 Quantum chemical analysis of the electronic structure and spectroscopic features of 2 All experimental and spectroscopic results point to a unique electronic structure of 2, which was thus analyzed by computational methods. Structure optimization of 2 validates the square-planar silicon (N-Si-N = 177 ) as the energetic minimum.…”

Recent developments in the chemistry of non-trigonal pnictogen pincer compounds: from bonding to catalysis

“…cooperative bond activation and small molecule activation (Scheme 1). 9, [14][15][16][17][18][19] The utilization of pincer ligands in p-block chemistry offers the possibility to further develop bond activation reactions by main group elements, including ligand cooperativity. Pincer ligands are usually coordinated to transition metals through salt elimination reactions or acid-base chemistry.…”

Metal–Ligand Cooperation Facilitates Bond Activation and Catalytic Hydrogenation with Zinc Pincer Complexes

“… 1 , 24 − 27 Importantly, the metal center does not change oxidation state in this process, and as a result, this activation mode could also be potentially operative with redox-innocent main group metals. 28 …”