Monocyclopentadienyl complexes of chromium, molybdenum or tungsten

A substituted monocyclopentadienyl, monoindenyl mono-fluorenyl or heterocyclopentadienyl complex of formula I

• [Y—M—Xn]m I,
• where:
• M is chromium, molybdenum or tungsten,
• Y is described by formula II
• where:
• E1-E5 are carbon or a maximum of one E1 to E5 is phosphorus or nitrogen,
• Z is a ring system represented by formulae
• wherein
• R18-R27 independently of one another are hydrogen, C1-C20-alkyl, C2-C20-alkenyl, C6-C20-aryl, alkylaryl having 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in the aryl radical, SiR173, or halogens, where the organic radicals R18-R27 may also be substituted by halogens, and in each case two geminal or vicinal radicals R18-R27 may also be linked to form a five- or six-membered ring,
• B is one of the following groups:
• and in addition, if Z is an unsubstituted, substituted or fused, partially unsaturated heterocyclic or heteroaromatic ring system, may alternatively be
• where
• L1 and L2 are silicon or carbon,
• k is 1, and is alternatively 0 if Z is an unsubstituted, substituted or fused, partially unsaturated heterocyclic or heteroaromatic ring system,
• X independently of one another, are fluorine, chlorine, bromine, iodine, hydrogen, C1-C10-alkyl, C2-C10-alkenyl, C6-C20-aryl, alkylaryl having 1-10 carbon atoms in the alkyl radical and 6-20 carbon atoms in the aryl radical, NR15R16, OR15, SR15, SO3R15, OC(O)R15, CN, SCN, β-diketonate, CO, BF4—, PF6—, or a bulky, non-coordinating anion,
• R1-R16 independently of one another, are hydrogen, C1-C20-alkyl, C2-C20-alkenyl, C6-C20-aryl, alkylaryl having 1 to 10 carbon atoms in the alkyl radical and 6-20 carbon atoms in the aryl radical, or SiR173, where the organic radicals R1-R16 may also be substituted by halogens, and in each case two geminal or vicinal radicals R1-R16 may also be linked to form a five- or six-membered ring,
• R17 independently of one another, are hydrogen, C1-C20-alkyl, C2-C20-alkenyl, C6-C20-aryl, alkylaryl having 1 to 10 carbon atoms in the alkyl radical and 6-20 carbon atoms in the aryl radical, and in each case two geminal radicals R17 may also be linked to form a five- or six-membered ring,
• n is 1, 2 or 3, and
• m is 1, 2 or 3.