As part of our ongoing interest in selective olefin oligomerisation, Tom Stennett’s recent work on new activation methods for such catalysts has just been published in Organometallics (Avoiding MAO: Alternative Activation Methods in Selective Ethylene Oligomerization). This describes a new ionic chromium(III) species [CrCl2(THF)4][Al(OC4F9)4] which is combined with diphosphines and small amounts of AlMe3 to yield active species for the selective oligomerization of ethylene. Complexes which are implicated as catalyst deactivation products are also isolated.