Abstract
AbstractReversible dissociation of H−X bond (M−L+H−X→M(X)‐L(H); ) is an important step during pre‐activation, catalysis and possible deactivation of acid‐base cooperative pincer based transition metal catalysts (M−L). Herein we carried out a high‐throughput computational investigation of the thermodynamic stability of different adducts in various functionalized Mn(I) based pincer complexes. We used a combination of density functional theory (DFT) and density functional tight binding (DFTB) calculations to analyze of >700 (M(X)‐L(H)) intermediates based on functionalized variants of four pincer type ligand scaffolds derived from PCP, CNC, PNP and SNS ligands. We discovered linear scaling relations between of various species. Strongest correlations were found between species of similar size and chemical nature e. g. correlated best with and worst with . Such scaling relations can be useful for property based screening of catalysts and selection of (co)solvent/substrate/base for optimized reaction conditions. We also investigated the influence of the ligand backbone and the functionalization of donor and backbone sites in the ligand. Our analysis reveals the crucial role of the second coordination sphere functionalization for the reactivity of the complexes with impact in some cases exceeding that of the variation of the functional groups directly attached to the donor atoms.
Highlights
Pincer complexes are important catalysts in organometallic chemistry for multiple applications such as transformation and synthesis of imines, amines, peptides, pyridines, pyrroles, acetals, and carboxylic acid derivatives, such as esters, ketones and amides.[1,2,3] Owing to their success withhydrogenation of a wide scope of substrates, pincer complexes have been adopted favorably by the pharmaceutical, fine chemicals and the energy industry[4]
Several successful examples of pincer catalysts based on earth abundant 3d transition metals (TMs) such as Fe and Mn have been realized in the last decade.[8,9]
We focused our investigation on the addition of HÀ X species (X = H, OH, MeO, EtO, i-PrO, t-BuO, Br) across the catalyst which is represented as MÀ L, where M represents the metal center and L represents the ligand
Summary
Most highly active pincers such as Ru-MACHO complex[5,6] and Nozaki’s Ir-PNP complex[7] are based on expensive Ru and Ir metals. Several successful examples of pincer catalysts based on earth abundant 3d transition metals (TMs) such as Fe and Mn have been realized in the last decade.[8,9] the activity and stability of such catalysts based on first row TMs remains a challenge. The development and optimization of catalysts based on 3d transition metals is an active and highly sought after area of research.[10,11,12] Manganese is attractive as the active metal in such catalysts in view of its high biocompatibility, which is of interest for industries in the food or pharmaceutical sector
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
