Jump to main content
Jump to site search
PLANNED MAINTENANCE Close the message box

Scheduled maintenance work on Wednesday 27th March 2019 from 11:00 AM to 1:00 PM (GMT).

During this time our website performance may be temporarily affected. We apologise for any inconvenience this might cause and thank you for your patience.


Issue 35, 2017
Previous Article Next Article

Rotaxane synthesis exploiting the M(I)/M(III) redox couple

Author affiliations

Abstract

In the context of advancing the use of metal-based building blocks for the construction of mechanically interlocked molecules, we herein describe the preparation of late transition metal containing [2]rotaxanes (1). Capture and subsequent retention of the interlocked assemblies are achieved by the formation of robust and bulky complexes of rhodium(III) and iridium(III) through hydrogenation of readily accessible rhodium(I) and iridium(I) complexes [M(COD)(PPh3)2][BArF4] (M = Rh, 2a; Ir, 2b) and reaction with a bipyridyl terminated [2]pseudorotaxane (3·db24c8). This work was underpinned by detailed mechanistic studies examining the hydrogenation of 1 : 1 mixtures of 2 and bipy in CH2Cl2, which proceeds with disparate rates to afford [M(bipy)H2(PPh3)2][BArF4] (M = Rh, 4a[BArF4], t = 18 h @ 50 °C; Ir, 4b[BArF4], t < 5 min @ RT) in CH2Cl2 (1 atm H2). These rates are reconciled by (a) the inherently slower reaction of 2a with H2 compared to that of the third row congener 2b, and (b) the competing and irreversible reaction of 2a with bipy, leading to a very slow hydrogenation pathway, involving rate-limiting substitution of COD by PPh3. On the basis of this information, operationally convenient and mild conditions (CH2Cl2, RT, 1 atm H2, t ≤ 2 h) were developed for the preparation of 1, involving in the case of rhodium-based 1a pre-hydrogenation of 2a to form [Rh(PPh3)2]2[BArF4]2 (8) before reaction with 3·db24c8. In addition to comprehensive spectroscopic characterisation of 1, the structure of iridium-based 1b was elucidated in the solid-state using X-ray diffraction.

Graphical abstract: Rotaxane synthesis exploiting the M(i)/M(iii) redox couple

Back to tab navigation

Supplementary files

Publication details

The article was received on 20 Jul 2017, accepted on 15 Aug 2017 and first published on 24 Aug 2017


Article type: Paper
DOI: 10.1039/C7DT02648J
Citation: Dalton Trans., 2017,46, 11645-11655
  • Open access: Creative Commons BY license
  •   Request permissions

    Rotaxane synthesis exploiting the M(I)/M(III) redox couple

    J. Emerson-King, R. C. Knighton, M. R. Gyton and A. B. Chaplin, Dalton Trans., 2017, 46, 11645
    DOI: 10.1039/C7DT02648J

    This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material.

    Reproduced material should be attributed as follows:

    • For reproduction of material from NJC:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
    • For reproduction of material from PCCP:
      [Original citation] - Published by the PCCP Owner Societies.
    • For reproduction of material from PPS:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
    • For reproduction of material from all other RSC journals:
      [Original citation] - Published by The Royal Society of Chemistry.

    Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

Search articles by author

Spotlight

Advertisements