Living Cyclopolymerization of 1,6-Heptadiyne Derivatives Using Well-Defined Alkylidene Complexes: Polymerization Mechanism, Polymer Structure, and Polymer Properties

Substituted polyacetylenes

“…Further, Mo carbene catalysts were synthesized and proven to elegantly induce living cyclopolymerization of 1,6-heptadiynes. 55 Ring-substituted phenylacetylenes were also adopted in the Mo carbene-initiated polymerization, leading to a finding that well-defined polymers are readily obtained with Mo carbenes ligated by less bulky alkoxy groups. 56 The initiation efficiencies of these living polymerizations are generally 100%, which enables the perfect control of molecular weight and simultaneously proves the validity of the metathesis mechanism.…”

Synthesis of chloro and methyl imido cyclopentadienyl molybdenum and tungsten complexes. X-ray molecular structures of WCp*Cl3(NtBu), MoCp*ClMe2(NtBu) and WCp*ClMe2(NtBu)

“…The solid was purilied by chromatography (ilorisil) ttsing hexane as eluent to afford after evaporation and cooling a red crystalline solid identified as complex 15 (0.4()g, 0.92retool, 359/ yield). 'H NMR (r3 ppm, in (2,6.. Me+C,,H O] (N'tht)] (16) An ampoule containing a solution of WCp*Me~(N'Bu) (15t (0.92~, "+ 12mmol~ and an excess of CN(2,6-Me,C+.H~/ (1.40o 10.56nmlol) in toluene (5()ml) was sealed under vacuum. By heating to 65°C a very slow reaction wits observed, that required 15 days to be complete, the colour of the solution changing from an orange to a deep red colour.…”

“…The chemistry of organoimido molybdenum and tungsten complexes has received much attention in the last few years because the imido ligand provides the desired electronic and steric control for molybdenum complexes to act as catalysts for ring-opening metathesis polymerization (ROMP) of cyclic olefins [ I ] and cyclopolymerization of acetylenes [ 2 ]. Formation of imido species has also been proposed as an intermediate step in the ammonoxidation of olefins [3].…”

Transition metal-based polymer chemistry: a critical micro-review

“…Dipropargylmalonate and derivatives thereof may be cyclopolymerized in a living manner using Mo(N-2,6-i-Pr 2 -C 6 H 3 /.CH-t-Bu)(OCMe(CF 3 / 2 / 2 . The resulting conjugated polymer contains both ve-and six-membered rings, resulting from competitive ®-and¯-insertions [105,106]. In accordance with the concept of 'small' alkoxides elaborated for ®-insertion (see below) [107,108], a catalyst containing large carboxylate groups, (Mo(N-2-t-buylphenyl)(CH-t-Bu)(O 2 CCPh 3 / 2 /, was found to produce a dipropargylmalonate polymer which solely contained sixmembered rings [109].…”