Issue 2, 2014

Synthesis and energetics of Tp′Rh[P(OMe)3](R)H: a systematic investigation of ligand effects on C–H activation at rhodium

Abstract

The thermal precursor Tp′Rh[P(OMe)3](Me)H was used to generate the active [Tp′Rh[P(OMe)3]] fragment, which activates C–H bonds of various hydrocarbons to form products of the type Tp′Rh[P(OMe)3](R)H (Tp′ = tris-(3,5-dimethylpyrazolyl)borate). Only one single activation product was observed in each case. The structures of Tp′Rh[P(OMe)3](R)X (X = H, Br, Cl) have been characterized by NMR spectroscopy, elemental analysis, and X-ray crystallography. The kinetics of reductive elimination of RH from Tp′Rh[P(OMe)3](R)H as well as competition experiments between substrates allow measurement of the Rh–C bond strengths relative to the Rh–Ph bond strength. Two separate linear correlations of the Rh–C bond energies versus H–C bond energies were found based on whether the alkyl group is α-substituted or not. While the correlation for α-substituted substrates gives a slope of 1.45, smaller than the slope (1.55) for unsubstituted hydrocarbons, the Rh–C bond energies of the former group are higher by ∼7 kcal mol−1. In comparison with the analogous [Tp′Rh(PMe3)] and [Tp′Rh(CNneopentyl)] systems, replacing the spectator ligand with a more electronic donating group slightly increases metal–carbon bond strengths as the trend in slopes of the correlations follows an order of CNneopentyl < P(OMe)3 ≤ PMe3.

Graphical abstract: Synthesis and energetics of Tp′Rh[P(OMe)3](R)H: a systematic investigation of ligand effects on C–H activation at rhodium

Supplementary files

Article information

Article type
Edge Article
Submitted
01 Okt 2013
Accepted
26 Nov 2013
First published
06 Dis 2013

Chem. Sci., 2014,5, 804-812

Synthesis and energetics of Tp′Rh[P(OMe)3](R)H: a systematic investigation of ligand effects on C–H activation at rhodium

Y. Jiao, W. W. Brennessel and W. D. Jones, Chem. Sci., 2014, 5, 804 DOI: 10.1039/C3SC52748D

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements