Preparation of Biscarboxylato Imido Alkylidene Complexes of Molybdenum and Cyclopolymerization of Diethyldipropargylmalonate To Give a Polyene Containing only Six-Membered Rings

Eine einfache Synthese von Polyacetylen‐Latices in wässrigem Medium

“…B. 1,3-(Cyclopent-1-enylen)vinylene [17,18] oder 1,3-(Cyclohexen-1-enylen)methylidene, [9,10] [RuCl 2 ( = CH-(2-(2-PrO)-C 6 H 4 ))(1,3-Bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazolin-2-yliden)], III, IV) [19] sind luft-und feuchtigkeitsbeständige Katalysatoren mit bemerkenswerter Aktivität, die in manchen Fällen sogar die der hoch aktiven Schrock-Katalysatoren erreicht. [20] Unge- 2 …”

Mo(CO)6-catalyzed cyclopolymerization of diethyl dipropargylmalonate to give a polyene containing only five-membered rings

“…Carbon resonances at 172.0 ppm (carbonyl carbon) and 57-58 ppm (quarternary carbon) are characteristic of five-membered rings, while resonances at 170.8 and 54 ppm are characteristic of six-membered rings. 10 Because the 13 C-NMR spectrum of poly(DEDPM) obtained from our work reveal just one peak at 171.9 ppm for the carbonyl carbon and one at 57.2 ppm for the quarternary carbon (Fig. 1), we conclude that they contain Ͼ 99% five-membered rings.…”

“…13 Further work has yet to be carried out to elucidate the mecha- nism and the general applicability of Mo(CO) 6 to other diynes.…”

“…The same group has even demonstrated 13 that the reaction can be further tuned up to give exclusively six-membered rings by replacing the ancillary alkoxides (OCMe(CF 3 ) 2 ) in the complex with bulky carboxylates ((O 2 CCPh 3 ) 2 ). The same authors proposed the mechanism consisting of addition of the first triple bond to an alkylidene to give exclusively a ␤-substituted metallacyclobutene intermediate, i.e., ␣ addition is sterically untenable, as may be deduced from eq.…”

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

“…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]. Quite recently, polymers containing solely ve-membered ring structures have been synthesized [110].…”