Nature Chemistry 3, 894–899 (2011); published online 25 September 2011; corrected after print 10 May 2013.

In the version of this Article originally published, in Table 1, the ferrocene-based ligands 4, 5, 7 and 8 should have had 1,2-substituted cyclopentadienyl rings rather than 1,3-substituted. This error has been corrected in the HTML and PDF versions of this Article.