Chromium(III) and chromium(IV) bis(trimethylsilyl) amido complexes as ethylene polymerisation catalysts

Oxidation of Cr[N(SiMe3)(2)](2)(THF)(2) with iodine and dicumyl peroxide results in tetrahedral Cr(IV)Cr[N(SiMe3)(2)](2)I-2 and trigonal planar Cr(III) Cr[N(SiMe3)(2)](OCMe2Ph)(2), respectively; both complexes have been characterised by single-crystal X-ray diffraction, and both are active for ethylene polymerisation with alkylaluminium co-catalysts.