Format

Send to

Choose Destination
See comment in PubMed Commons below
Chemistry. 2014 Mar 24;20(13):3825-30. doi: 10.1002/chem.201304243. Epub 2014 Feb 24.

Probing the limits of ligand steric bulk: backbone C-H activation in a saturated N-heterocyclic carbene.

Author information

1
Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR (UK).

Abstract

The consequences of extremely high steric loading have been probed for late transition metal complexes featuring the expanded ring N-heterocyclic carbene 6-Dipp. The reluctance of this ligand to form 2:1 complexes with d-block metals (rationalised on the basis of its percentage buried volume, % Vbur , of 50.8%) leads to C-H and C-N bond activation processes driven by attack at the backbone β-CH2 unit. In the presence of Ir(I) (or indeed H(+) ) the net result is the formation of an allyl formamidine fragment, while Au(I) brings about an additional ring (re-)closure step via nucleophilic attack at the coordinated alkene. The net transformation of 6-Dipp in the presence of [(6-Dipp)Au](+) represents to our knowledge the first example of backbone C-H activation of a saturated N-heterocyclic carbene, proceeding in this case via a mechanism which involves free carbene in addition to the Au(I) centre.

KEYWORDS:

CH activation; N-heterocyclic carbenes; gold; iridium; steric loading

PMID:
24616039
DOI:
10.1002/chem.201304243
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Loading ...
    Support Center