Coordination chemistry of the activation of [(triazacyclohexane)CrCl3] with [PhNMe2H][B(C6F5)4] and AlR3

Complexes of N-substituted 1,3,5-triazacyclohexanes with CrCl3 form 1:1 adducts with [PhNMe2H][B(C6F5)4] with increased solubility in toluene. Addition of AliBu3 leads to free PhNMe2 and a complex with [B(C6F5)4]− weakly coordinated to chromium via a meta-fluorine atom. This complex can polymerise and/or trimerise olefins similar to methyl aluminoxane activated complexes. Decomposition of the active complex involves transfer of the triazacyclohexane to aluminium leading to [(triazacyclohexane)AliBu2][B(C6F5)4] and [(arene)2Cr][B(C6F5)4]. These chromium(I) complexes have been characterised by X-ray crystallography and prove that chromium is reduced to the oxidation state +I during the catalysis.