Patent ID: 7084237

Claim:
In the process of polymerizing heterocyclic compounds, the improvement comprising using a polymerization catalyst of the formula wherein M is tin or germanium; L 1 and L 2 are individually selected from the group consisting of -E 14 (R 14 )R′ 14 )(R″ 14 )(R′ 15 ) and -E 16 (R 16 ), or together form -L′ 1 -A-L′ 2 ; A is a saturated or unsaturated chain comprising one, two or three elements of group 14 of the Periodic Table, substituted by one member selected from the group consisting of alkyl, cycloalkyl and aryl, each unsubstituted or substituted with a member selected from the group consisting of halogen, alkyl, aryl, nitro and cyano; L′ 1 and L′ 2 are individually selected from the group consisting of -E 14 (R 14 )(R′ 14 )-, E 15 (R 15 )- and -E 16 -; E 14 is an element of group 14 of the Periodic Table; E 15 is an element of group 15 of the Periodic Table; E 16 is an element of group 16 of the Periodic Table; R 14 , R′ 14 , R″ 14 , R 15 , R′ 15 and R 16 are individually selected from the group consisting of hydrogen, alkyl, cycloalkyl and aryl, unsubstituted or substituted with a member selected from the group consisting of halogen, aryl, cycloalkyl, aryl, nitro and cyano or -E′ 14 RR′R″-, E′ 14 is an element of group 14 of the Periodic Table; R, R′ and R″ are individually selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl, unsubstituted or substituted by a member selected from the group consisting of halogen, alkyl, aryl, nitro and cyano.