Coordination catalyst systems comprising intramolecularly stabilized organometallic compounds

A coordination catalyst system which comprises an intramolecularly stabilized organometallic compound of the formula I

• X.sup.1.sub.1 --M--(Z).sub.m (I),
• wherein
• M is an element selected from the group consisting of Mg, B, Al, Ga, In, Sn, Zn, Ti, Zr and lanthanides,
• l is the number 0, 1, 2 or 3,
• m is the number 1, 2, 3 or 4,
• where l+m corresponds to the oxidation state of M,
• X.sup.1 is CR.sup.1 R.sup.2 R.sup.3, NR.sup.1 R.sup.2 or OR.sup.1,
• R.sup.1, R.sup.2 and R.sup.3 are H, C.sub.1-6 -alkyl, where, in the case where 1=2, two radicals R.sup.1 together can also form a C.sub.2-6 -alkylene bridge,
• Z is ##STR3## n is the number 0, 1, 2 or 3, X.sup.2 is CH.sub.2, NH or a 5- or 6-membered aromatic, cycloaliphatic or heteroaromatic ring, in each case substituted by Y in the o-position,
• X.sup.3 is CH, N or a 5- or 6-membered aromatic, cycloaliphatic or heteroaromatic ring, in each case di-substituted with Y in the o,o'-positions,
• Y is (CH.sub.2).sub.o --NR.sup.4 R.sup.5, (CH.sub.2).sub.o --PR.sup.4 R.sup.5, (CH.sub.2).sub.o --OR.sup.4, or (CH.sub.2).sub.o --SR.sup.4,
• o is the number 1, 2 or 3, and
• R.sup.4 and R.sup.5 are hydrogen or C.sub.1-6 -alkyl,
• with the proviso that in the case where M=B, Al, Ga or In and Z=(CH.sub.2).sub.n --X.sup.2 --Y, m is not l.