This is a pre-copyedited, author-produced version of an article accepted for publication in Chemistry - A European Journal following peer review. The version of record is available http://onlinelibrary.wiley.com/doi/10.1002/chem.201705585/abstract;jsessionid=75FCD5D2363FBB135810470B4E73BAB3.f02t03#footer-article-info