Additions and corrections
Improved methods for the halogenation of the [HCB11H11]- anion
Weixing Gu, Billy J. McCulloch, Joseph H. Reibenspies and Oleg V. Ozerov
Chem. Commun., 2010, 2820–2822 (DOI: 10.1039/c001555e) Amendment published 05 August 2010
We have become aware of some issues with the undecachlorination Cs[HCB11H11] by SO2Cl2. In our hands, the reported reaction remains reproducible. However, it appears that the reproducibility hinges on a number of experimental details whose importance we did not realize at the time of publication.
We have only been able to reproduce the undecachlorination using "as-is", undistilled SO2Cl2 of the 97% grade from Aldrich (cat. # 320528-1L; reaction successful with different batches of this reagent) and the "as-is" Cs[HCB11H11] from Katchem. Distilled Aldrich SO2Cl2 or SO2Cl2 purchased from Acros (cat. # 169450010) led to only partial chlorination. Our successful reactions have been performed under uninterrupted illumination by fluorescent ceiling/hood lamps (including in different rooms), but no direct sunlight. Protection from light led to incomplete chlorination. Dislodging the precipitate that forms in the course of the reaction on the walls of the flask by gentle shaking may also be important for successful undecachlorination. Application of our protocol to a mixture of partially chlorinated carboranes did not lead to complete undecachlorination, even under conditions that would have produced the undecachlorinated product from the parent Cs[HCB11H11].
As of yet, we do not fully understand the confluence of factors that are responsible for the success of our specific undecachlorination protocol. We are working on the resolution and hope to publish our findings separately.
In addition, we incorrectly stated the length of the successful undecachlorination with SbCl5 on p. 2821 of the main text to be 24 h. The correct time is 3 days, as reported in the ESI.
We regret the inadvertent omissions. We are grateful to Profs. C. A. Reed and R. Wehmschulte for bringing some of the above issues to our attention.
The Royal Society of Chemistry apologises for this error and any consequent inconvenience to authors and readers.
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