Catalysts and processes for the polymerization of olefins

A catalyst for the polymerization of olefins comprising the product obtained by contacting the following components:

• (A) a cyclopentadienyl compound of the formula (I):
• (C.sub.5 R.sup.1.sub.x-m H.sub.5-x)R.sup.2.sub.m (C.sub.5 R.sup.1.sub.y-m H.sub.5-y).sub.n MQ.sub.3-n (I)
• in which M is Ti, Zr or Hf, C.sub.5 R.sup.1.sub.x-m H.sub.5-x and C.sub.5 R.sup.1.sub.y-m H.sub.5-y are cyclopentadienyl rings substituted in the same way or different ways, the substituents R.sup.1 which can be identical or different are alkyl, alkenyl, aryl, alkylaryl or arylalkyl radicals which have 1 to 20 carbon atoms and can also contain atoms of Si or Ge, or groups Si(CH.sub.3).sub.3, or two or four substituents R.sup.1 of one and the same cyclopentadienyl group can also form one or two rings having 4 to 6 carbon atoms, R.sup.2 is a group which as a bridge links the two cyclopentadienyl rings and is selected from the group consisting of CR.sup.3.sub.2, C.sub.2 R.sup.3.sub.4, SiR.sup.3.sub.2, Si.sub.2 R.sup.3.sub.4, GeR.sup.3.sub.2, Ge.sub.2 R.sup.3.sub.4, R.sup.3.sub.2 SiCR.sup.3.sub.2, NR.sup.1 and PR.sup.1, with the substituents R.sup.3 which can be identical or different being R.sup.1 or hydrogen or two or four substituents R.sup.3 can also form one or two rings having 3 to 6 carbon atoms, the substituents Q which can be identical or different are halogen, hydrogen, R.sup.1, OR.sup.1, SR.sup.1, NR.sup.1.sub.2 or PR.sup.1.sub.2, m can be 0 or 1, n can be 0 or 1, being 1, if m=1, x is an integer of between (m+1) and 5, and y is an integer of between m and 5;
• and
• (B') the product of the reaction between water and an organometallic aluminum compound of the formula (II):
• Al(CH.sub.2 --CR.sup.4 R.sup.5 R.sup.6).sub.w R.sup.7.sub.y H.sub.z(II)
• wherein in the (CH.sub.2 --CR.sup.4 R.sup.5 R.sup.6) groups, which are the same or different, R.sup.4 is an alkyl, alkenyl or arylalkyl group having from 1 to 10 carbon atoms, R.sup.5 is an alkyl, alkenyl, aryl, arylalkyl or alkylaryl group having from 3 to 50 carbon atoms which is different from a straight alkyl or alkenyl group and, optionally, R.sup.4 and R.sup.5 fused together can form a ring having from 4 to 6 carbon atoms, R.sup.6 is hydrogen or an alkyl, alkenyl or arylalkyl group having from 1 to 10 carbon atoms, the R.sup.7 substituents, same or different, are alkyl, alkenyl, aryl, arylalkyl or alkylaryl radicals containing from 1 to 10 carbon atoms and, optionally, can contain Si or Ge atoms, w is 1, 2 or 3, z is 0 or 1, y=3-w-z, the molar ratio between the organometallic aluminum compound and the water being comprised between 1:1 and 100:1.