Collect. Czech. Chem. Commun. 1998, 63, 1815-1838

Comparative Study of Polymerization of 2-, 3- and 4-Iodophenylacetylenes with Rh-, Mo- and W-Based Catalysts

Jiří Vohlídala, Jan Sedláčeka, Nikolay Pateva, Marta Pacovskáa, Olivier Lavastreb, Sandrine Cabiochb, Pierre H. Dixneufb, Vratislav Blechtac, Pavel Matějkad and Hynek Balcare

a Department of Physical and Macromolecular Chemistry, Laboratory of Specialty Polymers, Charles University, 128 40 Prague 2, Czech Republic
b Laboratoire de Chimie de Coordination et Catalyse, URA CNRS 415, Campus de Beaulieu, Université de Rennes 1, F-35042 Rennes, France
c Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 165 02 Prague 6-Suchdol, Czech Republic
d Department of Analytical Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
e J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, 182 23 Prague 8, Czech Republic


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.

Keywords: Iodophenylacetylene; Substituted polyacetylenes; Poly(phenylacetylene); Conjugated polymers; Metathesis polymerization; Tungsten; Molybdenum; Rhodium; Raman spectroscopy.