ANIONIC RING-OPENING POLYMERIZATION OF 1,2,2-TRIMETHYL-1-PHENYL-1,2-DISILACYCLOPENTANE

The anionic ring-opening polymerization of 1,2,2-trimethyl-1-phenyl-1, 2-disilacyclopentane took place in THF at 0 similar to-78 degrees C. T he initiators were ''Bu(4)NF, PhMe(2)SiK, and (PhMe(2)Si)(2)Cu(CN)Li-2 . When PhMe(2)SiK was used, the addition of HMPA was required for the polymerization. The polymerization initiated with (PhMe(2)Si)(2)Cu(CN) Li-2 showed a living character to some extent. The product polymers co ntained not only a head-to-tail structure but also head-to-head and ta il-to-tail structures, whose amounts were dependent on the initiator: 4% (''Bu(4)NF), 30% (PhMe(2)SiK), and 12% ((PhMe(2)Si)(2)Cu(CN)Li-2). These values reflect the efficiency of the phenyl group to stabilize t he silyl anion that is the propagating end.