Treatment of the rhodium pincer complexes [RhCl(RPm)] (RPm = N,N′-bis(di-R-phosphinomethyl)perimidinylidene, R = Ph, Cy) with triphenylcyclopropenium hexafluorophosphate afford rhodacyclobutadiene complexes. These in turn react with activated alkynes (RC≡CCO2Me, R =...