Issue 10, 2015

Pd-η3-C6H9 complexes of the Trost modular ligand: high nuclearity columnar aggregation controlled by concentration, solvent and counterion

Abstract

Under optimised conditions, the Trost modular ligand (TML) series induces high levels of asymmetric induction in an extraordinarily wide range of reactions involving palladium π-allyl intermediates. Prior mechanistic investigations into reactions involving Pd-η3-C6H9 intermediates have focussed on the monomeric 13-membered ring formed via P,P-chelation of the ligand to Pd. However, it is also recognised that ring-opening oligomerisation provides a pool of high nuclearity Pd-η3-C6H9 species that, by affording a low level, or even the opposite sense, of asymmetric induction relative to the mononuclear species, are responsible for a reduction in selectivity under non-optimised conditions. Herein we describe an investigation by NMR spectroscopy, molecular mechanics, molecular dynamics, and small-angle neutron scattering (SANS), of a Pd-η3-C6H9 cation bearing the 1,2-diaminocyclohexane TML ligand (2). Using both nondeuterated and perdeuterated (D47) isotopologues of the resulting complexes ([1]+), we show that a two-stage oligomerisation-aggregation process forms self assembled cylindrical aggregates of very high nuclearity (up to 56 Pd centres). We also investigate how concentration, solvent and counter-anion all modulate the extent of oligomerisation.

Graphical abstract: Pd-η3-C6H9 complexes of the Trost modular ligand: high nuclearity columnar aggregation controlled by concentration, solvent and counterion

Supplementary files

Article information

Article type
Edge Article
Submitted
02 apr 2015
Accepted
12 jun 2015
First published
15 jul 2015
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2015,6, 5793-5801

Pd-η3-C6H9 complexes of the Trost modular ligand: high nuclearity columnar aggregation controlled by concentration, solvent and counterion

D. T. Racys, J. Eastoe, P. Norrby, I. Grillo, S. E. Rogers and G. C. Lloyd-Jones, Chem. Sci., 2015, 6, 5793 DOI: 10.1039/C5SC01181G

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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