HIGHLY STEREOREGULAR POLYMERIZATION OF AROMATIC ACETYLENES BY [RH(NORBORNADIENE)CL](2) CATALYST

The highly stereoregular polymerization of phenylacetylene and its hom ologues has been achieved by a Rh complex, [Rh(norbornadiene)Cl](2) wh ere an unusual organic base such as triethylamine was used as the poly merization solvent, and cis-transoid polymers were selectively obtaine d in very high yields. Further, the organic base was considered to wor k as the dissociator of the dimeric catalyst, [Rh(norbornadiene)Cl](2) into the monomeric species responsible to the initiation species in t his polymerization. The resulting poly(o-methoxyphenylacetylene) was f ound to be isomerized from cis to trans form when the polymer was comp ressed with pressure of 200 Kg/cm(2). The pi-radical spins were found to be created by the ruptures of the C=C bonds in the cis form by the compression. We found that the broad signals in the ESR spectrum of th e PPA polymer are created by storage at 77K. The appearance of the bro ad signals was interpreted in terms of an aggregation of the radical s pins produced during and/or after the polymerization of PPA where inte rnal fields with different energy levels between the spins are generat ed. The broad signals of the PPA polymer induced by cooling at 77 K is responsible to the magnetic spin odering which was called ''Time Indu ced Magnetic Spin Order (TIMSO)'' phenomenon.