Bipyrrolidine salan alkoxide complexes of lanthanides: synthesis, characterisation, activity in the polymerisation of lactide and mechanistic investigation by DOSY NMR

Abstract

and revealed a dinuclear catalytically active species.

Synthesis of Enantiopure Lanthanide Complexes Supported by Hexadentate N,N′-Bis(methylbipyridyl)bipyrrolidine and Their Circularly Polarized Luminescence

“…To date, the chiral 2,2′-bipyrrolidine moiety had not yet been investigated for CPL applications. Additionally, only one example of a bipyrrolidine-based ligand coordinated to lanthanides has been reported, 15 and only derivatives of the achiral mesobipyrrolidine were evaluated. Herein, we report the coordination chemistry of hexadentate ligands based on the chiral 2,2′bipyrrolidine scaffold to several emissive lanthanides (Sm, Eu, Tb, and Dy).…”

The interpretation of small molecule diffusion coefficients: Quantitative use of diffusion-ordered NMR spectroscopy

“…While the SEGWE method was explicitly designed for small molecules, containing only lighter atoms such as C, H, and O, this has not stopped its use in the analysis of compounds and complexes containing aluminium [254][255][256], cobalt [257], copper [258,259], gold [260], heavy alkaline earth elements [261], all heavier Group 14 elements [262], iridium [263], nickel [264], palladium [236,265,266], samarium [267], selenium [268], silver [269,270], titanium [271], uranium [272], yttrium [273,274], and zinc [275,276]. While caution might be well advised in the extrapolated use of an effective density optimised using a training set consisting solely of small, organic molecules, it was noted in [259] that for the species studied therein, the ligand units used made up the bulk of the molecular weight, 540 g mol −1 , compared with the heavier Cu (64 g mol −1 ) atom and halides (35 g mol −1 for Cl, 127 g mol −1 for I).…”

Aluminum Complexes of Octahydrophenanthroline‐Based Salophan Ligands: Coordination Chemistry and Activity in the Ring‐Opening Polymerization of Lactide

“…Salans are sequential tetradentate‐dianionic {ONNO}‐type ligands that include sp 3 N‐donors and two phenolate arms connected to the N‐donors via methylene bridges With a typical two‐carbon bridge between the N‐donors, salans bind to metals forming a 6–5–6 tri‐chelate array. Complexes of salans around various transition and main‐group metals of various coordination numbers have been described in the past two decades, and have been employed as catalysts in different transformations including the stereoselective polymerization of alpha‐olefins, and the asymmetric oxidation of sulfides and olefins . The sequential nature of the salans, combined with the flexibility around the N‐donors, may lead to several modes of wrapping of the salans around the metal centers, and consequently to stereoisomer mixtures.…”