Issue 43, 2011

Facile η5–η3 hapticity interconversion in pentamethylcyclopentadienyl ruthenium(ii) complexes containing a phenylmethallyl (“open indenyl”) ligand

Abstract

The indenyl effect has been introduced to pentadienyl (“open cyclopentadienyl”) chemistry by preparation of the phenylmethallyl (“open indenyl”) ligand oIndMe. The reaction of its potassium salt K(oIndMe) with [(η5-C5Me5)RuCl]4 afforded the sandwich complex [(η5-C5Me5)Ru(η5-oIndMe)] (1), which, upon treatment with PMe3, CO, and 2,6-dimethylphenyl isocyanide (CN-o-Xy), easily underwent η5–η3 hapticity interconversion and formed the complexes [(η5-C5Me5)Ru(η3-oIndMe)(L)] (2, L = PMe3; 3, L = CO; 4, L = CN-o-Xy). In these complexes, the η3-bound phenylmethallyl ligand adopts an anti-conformation with regard to the relative positions of the phenyl and methyl substituents. For the PMe3 complex anti-2, slow conversion to the syn-isomer was observed, and this equilibrium reaction was monitored by NMR spectroscopy at 50 °C to determine a first order rate constant of k323 K = 6.57 × 10−6 (± 0.02 × 10−6) s−1 and an activation barrier of ΔG° = 26.8 kcal mol−1. DFT calculations afforded a stabilization of syn-2 and syn-3 by ΔG298 = −1.54 and −1.74 kcal mol−1 over the respective anti-isomer.

Graphical abstract: Facile η5–η3 hapticity interconversion in pentamethylcyclopentadienyl ruthenium(ii) complexes containing a phenylmethallyl (“open indenyl”) ligand

Supplementary files

Article information

Article type
Paper
Submitted
27 Jun 2011
Accepted
22 Aug 2011
First published
27 Sep 2011

Dalton Trans., 2011,40, 11511-11518

Facile η5–η3 hapticity interconversion in pentamethylcyclopentadienyl ruthenium(II) complexes containing a phenylmethallyl (“open indenyl”) ligand

A. Glöckner, Ò. Àrias, T. Bannenberg, C. G. Daniliuc, P. G. Jones and M. Tamm, Dalton Trans., 2011, 40, 11511 DOI: 10.1039/C1DT11436K

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