Method of preparing homopolymers of conjugate dienes and copolymers of conjugate dienes with other dienes or vinyl aromatic compounds

The method of preparing homopolymers of conjugated dienes or copolymers of conjugated dienes with another diene or with vinyl aromatic compounds in which the vinyl content is above 70%, characterized by use of a catalytic composition comprising:

• (a) an organomagnesium compound MgR.sup.1 R.sup.2 (I), wherein R.sup.1 and R.sup.2 are selected from the group consisting of aliphatic, alicyclic or aromatic hydrocarbons radicals having from 2 to 20 carbon atoms, which may be the same or different,
• (b) an organoaluminium compound selected from the group consisting of those represented by following formulae (II) to (V):
• ##STR3## where the groups R.sup.3 to R.sup.14 can be H or the same or different radicals, selected from the group of normal, secondary or tertiary alkyl, cycloalkyl or aryl radicals containing 2 to 20 carbon atoms, and
• (c) an organic barium, strontium or calcium compound selected from the group consisting of those represented by the following formulae (VI) to (VII):
• ##STR4## where Me is at least one metal selected from the group consisting of Ba, Ca, Sr, where R.sup.15 to R.sup.18 are selected from the group consisting of alkyl, cycloalkyl, aryl, phenoxy or alkoxy from 4 to 20 carbon atoms, which may be the same or different.