Stereospecific carbene polymerisation with oxygenated Rh(diene) species

Breath-taking activation: Stereoregular carbene polymerization proceeds via cationic [(allyl)RhIII–polymeryl]+ species. These are most efficiently generated by oxygenation of the [(diene)RhI] precatalysts, which involves an unusual rearrangement of 2-rhodaoxetane intermediates. This discovery gives detailed insight in the reaction mechanism.Financial support from the European Research Council (ERC, grant agreement 202886-CatCIR), the Netherlands Organization for Scientific Research (NWO-CW), the Dutch Polymer Institute (DPI projects no. 646/647), the University of Amsterdam, the DFG (SFB-583 and Major Research Instrumentation Program) and MICINN/FEDER (Projects CTQ2008-03860 and CTQ2011-22516) is gratefully acknowledged.Peer Reviewe