Issue 21, 2016

Coordination chemistry of a calix[4]arene-based NHC ligand: dinuclear complexes and comparison to IiPr2Me2

Abstract

The preparation and coordination chemistry of 5,17-bis(3-methyl-1-imidazol-2-ylidene)-25,26,27,28-tetrapropoxycalix[4]arene (1) is described. Starting from the bis(imidazolium) pro-ligand 1·2HI, the free carbene 1 was readily generated in solution through deprotonation using K[OtBu] and its reactivity with rhodium(I) dimers [Rh(COD)Cl]2 (COD = 1,5-cyclooctadiene) and [Rh(CO)2Cl]2 investigated. Dinuclear complexes were isolated in both cases, where the calix[4]arene-based NHC ligand adopts a bridging μ2-coordination mode, and in one case characterised in the solid-state by X-ray diffraction. Using instead an isolated and well-defined (mononuclear) silver transfer agent, generated by reaction of 1·2HI with Ag2O in the presence of a halide extractor, reactions with [Rh(COD)Cl]2 and [Rh(CO)2Cl]2 produced cationic dinuclear complexes bearing μ2-1 and μ2-Cl bridging ligands. The structural formulation of the novel dinuclear adducts of 1 was aided through spectroscopic congruence with model complexes, containing monodentate 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (IiPr2Me2).

Graphical abstract: Coordination chemistry of a calix[4]arene-based NHC ligand: dinuclear complexes and comparison to IiPr2Me2

Supplementary files

Article information

Article type
Paper
Submitted
14 Mar 2016
Accepted
03 May 2016
First published
10 May 2016
This article is Open Access
Creative Commons BY license

Dalton Trans., 2016,45, 8945-8955

Coordination chemistry of a calix[4]arene-based NHC ligand: dinuclear complexes and comparison to IiPr2Me2

R. Patchett and A. B. Chaplin, Dalton Trans., 2016, 45, 8945 DOI: 10.1039/C6DT01001F

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