Sterically rigid bismuth pincer complexes; observation of the growing polymer chain in polar monomer polymerisation

Abstract

A family of pyridine dipyrrolide bismuth complexes (Mes,PhL)MX (1–6 (M = Bi, X = O-2,6-Me-C6H3 = OXyl (1); M = Sb, X = OXyl (2); M = Bi, X =...

Speciation and Photoluminescent Properties of a 2,6‐Bis(pyrrol‐2‐yl)pyridine in Three Protonation States

“…Since then, complexes with unusual molecular and electronic structures imparted by the PDP framework have been reported for many elements across the d‐block [18–21] and have found application in catalysis, [22,23] group transfer reactions, [24–27] and small molecule activation [25,28] . Going beyond transition metal complexes, main group compounds with PDP ligands were first reported by Turner [29] in 2019 and have subsequently been shown to possess unique reactivity and catalytic activity [30–32] . In 2022, further expansion into the f‐block elements was accomplished through the report of the first uranium PDP complexes [33,34] …”

“…[25,28] Going beyond transition metal complexes, main group compounds with PDP ligands were first reported by Turner [29] in 2019 and have subsequently been shown to possess unique reactivity and catalytic activity. [30][31][32] In 2022, further expansion into the f-block elements was accomplished through the report of the first uranium PDP complexes. [33,34] A particular focus of our ongoing studies of transition metal and main group PDP compounds are their remarkable photophysical and photochemical properties.…”

Planar bismuth triamides: a tunable platform for main group Lewis acidity and polymerization catalysis

“…In contrast, compared to other bismuth systems utilized for this polymerization, 3b is able to produce polymers with high molecular weights and lower dispersity. 88–94 For example, diphenyl bismuth bromide or bismuth subsalicylate are able to proceed at greater rates and produce polymers of similar (or higher) molecular weights, the dispersities reported for these systems are higher (1.5–2) than observed here. 93,94…”

“…In contrast, compared to other bismuth systems utilized for this polymerization, 3b is able to produce polymers with high molecular weights and lower dispersity. [88][89][90][91][92][93][94] For example, diphenyl bismuth bromide or bismuth subsalicylate are able to proceed at greater rates and produce polymers of similar (or higher) molecular weights, the dispersities reported for these systems are higher (1.5-2) than observed here. 93,94 To probe the degree of control over molecular weight control which could be achieved using 3b, the catalyst loading of polymerizations of 3-caprolactone and rac-lactide were varied to observe the effect on M n .…”

Heteroleptic Calcium Complexes Supported by a Phenoxy-Imine NON Ligand: Polymerization of Cyclic Esters by a Ligand-Assisted, Activated-Monomer Mechanism

“…Similar observations have previously been made by Turner and co-workers in their report investigating the catalytic capability of bismuth pyridine dipyrrolide complexes pincer complexes. 40 For the polymerization of rac-LA using 6/BnOH, integration for the sii, iii, and iis tetrads are in a 1:1:1 ratio in the 1 H{ 1 H} NMR spectrum and so a chain end control can be postulated (Figure S35a). However, for the analogous polymerization with meso-LA, the integration for the ssi, sis, isi, and iss tetrads are in a 1:2:1:1 ratio (Figure S35b).…”