| abstract |
The invention concerns the use of stannylenes and germylenes of general formula (1) wherein: n n n M represents a tin or germanium atom; L 1 and L 2 independently represent a group of formula: —E 14 (R 14 )(R′ 14 )(R″ 14 ), —E 15 (R 15 )(R′ 15 ) or —E 16 (R 16 ), or together form a chain of formula —L′ 1 —A—L′ 2 ; A represents a saturated or unsaturated chain comprising one, two or three elements of group 14; L′ 1 and L′ 2 , represent, independently, a group of formula: —E 14 (R 14 )(R′ 14 )—, E 15 (R 15 )—or —E 16 —E 14 is an element of group 14; E 15 is an element of group 15; E 16 is an element of group 16; R 14 , R′ 14 , R″ 14 , R 15 , R′ 15 and R 16 represent variable groups as polymerisation catalysts of heterocycles. |