Aluminum-Containing Heterobimetallic Complexes as Versatile Platforms for Homogeneous Catalysis

Aluminum Complexes Bearing Aminoquinoline Ligands with Different Pendant Donors: Remarkable Impact of Hemilability on the Ring-Opening Polymerization of ε-Caprolactone

“…20−27 Among numerous metal-based catalysts, Al complexes are especially attractive because of the large abundance of this element in the earth's crust and its low cost and high Lewis acidity. 28,29 Moreover, both the catalytic activity and selectivity of Al complexes can be much enhanced by tuning the coordination environment of the metal center by introducing suitable ancillary ligands. 30−40 This accounts for the development of numerous bidentate or multidentate ligands containing different chemical functionalities such as hard (O− or N−) and soft (S− or P−) donors.…”

“…Aliphatic polyesters have received increasing attention because of growing concerns for a sustainable environment. − Among them, poly­(ε-caprolactone) (PCL) displays appropriate degradability, excellent biocompatibility, and interesting permeability toward water and small molecules, which make it one of the most popular materials for medical devices, tissue engineering, and drug delivery. , The superior properties of PCL highly rely on a well-defined structure, predictable molar mass ( M n ), low dispersity ( Đ ), and desirable end groups and are best achieved by ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) under mild conditions. − Although metal-based catalysts are predominant in this field because of their high activity, selectivity, and diversity, − competitive organocatalysts and dual catalytic systems have recently emerged. − Among numerous metal-based catalysts, Al complexes are especially attractive because of the large abundance of this element in the earth’s crust and its low cost and high Lewis acidity. , Moreover, both the catalytic activity and selectivity of Al complexes can be much enhanced by tuning the coordination environment of the metal center by introducing suitable ancillary ligands. − This accounts for the development of numerous bidentate or multidentate ligands containing different chemical functionalities such as hard (O– or N–) and soft (S– or P–) donors. Such hybrid ligands often display hemilabile properties of catalytic relevance owing to their ability to facilitate substrate coordination by opening a coordination site and to stabilize reactive intermediates in the transition state. − This concept is now widely applied in a number of catalytic reactions, including alkylation, cross-coupling, carbonylation, hydroformylation, hydrogenation, olefin polymerization, and ring-opening metathesis polymerization. − However, there are only a few examples of ROP catalysts supported by hemilabile ligands.…”

Solution Structure and Dynamics of Hf–Al and Hf–Zn Heterobimetallic Adducts Mimicking Relevant Intermediates in Chain Transfer Reactions

“…Combinations of group IV transition metal complexes and main group metal alkyls and/or hydrides (such as AlR 3 or ZnR 2 ) are employed in several stoichiometric and catalytic transformations, including metalation of unsaturated substrates, − olefin oligomerization, − and olefin polymerization, − especially chain shuttling polymerization (CSP) − and coordinative chain transfer polymerization (CCTP). − …”

Coupling homogeneous and heterogeneous catalysis for the efficient and selective activation of H2O2

“…Scientists have been fascinated by the many diametric features of homogeneous and heterogeneous catalysis. 1–3 Homogeneous catalysts generally contain defined and isolated metal sites that allow for high activity 4,5 but suffer from difficulty in recycling/reuse and limited control over selectivity. In contrast, heterogeneous catalysts are readily recyclable and can offer tailorable active sites for a given catalytic reaction.…”