2-, 3- and 4-Iodophenylacetylenes (IPA) have been polymerized with [Rh(cod)(OCH3)]2 complex in THF (system Rh), MoCl5 in benzene (Mo), WOCl4 in benzene (WB) and WOCl4/Ph4Sn in benzene-dioxane 1 : 1 (WD). All the systems provide poly(iodophenylacetylene)s (PIPA) and diverse amounts of oligomers (mostly cyclic trimers and tetramers) but the system 2-IPA/Rh that provides mostly dimers only. 2-IPA has also been polymerized with MoOCl4/Bu4Sn/EtOH in toluene (Masuda's catalyst system), however, neither living nor pseudo-living polymerization has been observed. The ring-iodine steric effects control the polymerization activity of the Rh and WB systems and the oligomerization activity of the Mo system. The ring-iodine electronic effects are important for the oligomerization activity of the Rh and WB systems and both oligomerization and polymerization activity of the WD system. Both types of the ring-iodine effect are important for polymerization activity of the Mo system. Rh catalyst provides high-cis-transoid, head-to-tail (HT) 3-PIPA that slowly isomerizes in CDCl3 solution to an insoluble trans-polymer. In the case of 4-PIPA, the isomerization is extremely fast upon polymer entering into contact with methanol. On the basis of spectral changes accompanying this isomerization, the Raman band at 1 338 cm-1 is assigned to the presence of HT sequences of both cis-transoid and trans-cisoid type. The other catalysts provide irregular PIPAs with content of both cis units and HT sequences decreasing in order Mo > WD > WB. Solubility of PIPA samples is shown as a result of complex interplay of the ring-iodine position and the polymer microstructure and molecular weight.

The selective, terminal triple bond polymerization of HC⋮C−C6H4−C⋮C−SiiPr3 (1) and HC⋮C−C6H4−C⋮C−C6H4−C⋮C−SiiPr3 (2) yields soluble, high-MW polyacetylenes P1 and P2 with phenyleneethynylene-type pendant chains. The [Rh(cod)(OCH3)]2- and MoCl5-based catalysts show 100% polymerization selectivity to terminal triple bonds and give high-cis (NMR:  Rh, 94% cis; Mo, 70% cis) polymers having a medium extent of π-conjugation. WOCl4-based catalysts reacting in benzene marginally also insert internal triple bonds and give low-cis polymers (<10% cis) having a high extent of conjugation. Addition of 1,4-dioxane to the WOCl4-based catalyst considerably reduces or even eliminates the internal triple bond insertion and increases the polymer molecular weight, cis-unit content (≈35% cis) and extent of π-conjugation. The π−π* band of P1 pendant groups is closely correlated with the polymer microstructure:  the cis-unit content in P1 can be reliably ascertained from the A 292/A 268 UV-absorbance ratio. Raman bands of the main-chain ν(CC) mode exhibit both frequency and intensity dispersion with extent of conjugation. On the other hand, only intensity dispersion is conclusively observed for the ν(Ph−Cchain) band at 1341 cm-1 that, upon correction to the dispersion effect, is in a good correlation with the cis-unit content obtained from NMR spectra. Xerographic and transient photoconductivity measurements have shown that the photogeneration in these polymers proceeds through the side group excited states, and the charge carrier's (holes) transport is controlled by hopping between the main chain conjugated sequences.

3 ) containing a small amount of C3CH groups that is soluble in aromatic and low-polarity solvents. Its solubility, however, decreases upon storage in the solid state, probably due to a subsequent crosslinking. The 13 C NMR, IR, UV-vis and Raman spectra of the monomer and polymers are reported.

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