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 (AlBu3)-Bu-i 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) (AlBu2)-Bu-i][B(C6F5)(4)] and [(arene)(2)Cr][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. (C) 2003 Elsevier B.V. All rights reserved.