Vinyltitanium as an initiator for the polymerization of acetylene

Abstract

The preparation of lustrous conducting polyacetylene films by the polymerization of acetylene with vinyltitanium species as initiators was studied. Organotitanium species were generated by the alkylation of titanium vinylcarbene complexes with tert‐butyl chloride. Solid‐state 13C NMR and IR analyses of the obtained polyacetylene indicated that polyacetylene with a trans configuration was produced. The use of titanocene(II) species Cp2Ti[P(OEt)3]2 and titanium vinylcarbene complexes for the preparation of polyacetylene films was also studied. The morphology of the films and the mechanisms of polymerization are discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2663–2669, 2002

Dielectric Barrier Discharge at Atmospheric Pressure as a Tool to Deposit Versatile Organic Coatings at Moderate Power Input

“…Unfortunately, the latter region is highly obscured by chemical shifts originating from carbon atoms of C*O, C*‐CC and C*C(O). Although not perfectly resolved, the double bond region in the 13 C MAS NMR spectrum shows two signals which can be attributed due to cis (127 ppm) and trans (136 ppm) double bonds in agreement with those of cis ‐ trans oid polyacetylene isomer 41,42. In addition, when triple CC bonds are highly conjugated in a polymer, the resonance appears at higher chemical shifts (90–110 ppm).…”

Selective Catalytic Dimerization of Neohexene by [Cp*Ti(NPtBu3)Me][B(C6F5)4]

“…A similar mechanism has been proposed for the dimerization of ethylene by an electron-poor iridium complex, (κ 2 -O,O -acetylacetonate) 2 Ir(III)(CHCH 2 )(Py), which has been shown to proceed through olefin insertion into a metal-vinyl intermediate followed by C−H activation to liberate the dimeric products . The neutral titanium-vinyl complex Cp 2 TiCl(CHCHCH{R}C{CH 3 } 3 ) (R = {CH 2 } 2 Ph, CH 2 Ph, {CH 2 } 7 CH 3 ) is also known to be an efficient initiator for polymerization of acetylene to trans -polyacetylene even at −40 °C, suggesting that a cationic titanium-vinyl complex would be highly reactive toward olefin insertion even at low temperature. Although alkyne addition to the highly substituted titanium-vinyl complex proceeds in a syn fashion, rapid isomerization to the more thermodynamically stable trans vinyl complex is presumed to occur prior to subsequent acetylene additions.…”

Preparation of Osmium η3-Allenylcarbene Complexes and Their Uses for the Syntheses of Osmabenzyne Complexes

“…The formation of the η 3 -allenylcarbene complexes OsCl 2 (CAr-η 2 -CHCCHAr)­(PPh 3 ) 2 from the reactions of HCCAr with OsCl 2 (PPh 3 ) 3 ( 1 ) is interesting for the following reasons. First of all, although η 3 -vinylcarbene complexes − are very common, reported η 3 -allenylcarbene complexes are still rare. − Second, although coupling reactions of vinylidene species with alkynes to give allenylcarbene or metallacyclobutene intermediates have been proposed as early as 1980 as some of the key steps in metal-catalyzed oligomerization and polymerization of alkynes, very few examples of such coupling reactions have been documented. The η 1 -allenylcarbene complexes Cp­(CO)­(NO)­WC­(NEt 2 )­C­(R)CHCMe 3 (R = Me, Et) were isolated from the reactions of Cp­(CO)­(NO)­WCCHCMe 3 with the electron-rich alkynes RCCNEt 2 .…”