Chromium(iii) and chromium(iv) bis(trimethylsilyl)amido complexes as ethylene polymerisation catalysts

Oxidation of Cr[N(SiMe(3))(2)](2)(THF)(2) with iodine and dicumyl peroxide results in tetrahedral Cr(iv) Cr[N(SiMe(3))(2)](2)I(2) and trigonal planar Cr(iii) Cr[N(SiMe(3))(2)](OCMe(2)Ph)(2), respectively; both complexes have been characterised by single-crystal X-ray diffraction, and both are active for ethylene polymerisation with alkylaluminium co-catalysts.