Metathesis Polymerization of Substituted Acetylenes and Norbornene by M(CO)6-Ph2CCl2-hν (M=Mo, W) Catalysts

Abstract

ABSTRACT:The M(CO)6-Ph2 CCl2-hv (M = W, Mo) systems worked as effective catalysts in the metathesis polymerization of substituted acetylenes and norbornene. Thus, W(CO) 6-Ph 2 CC1 2 -hv polymerized phenylacetylene in toluene at 30''C for 24 h to provide a polymer with M w 30000 in 70% yield, and polymerized norbornene at 60°C to give a polymer with M., 26000 quantitatively. Ph 2 CCl2 and ultraviolet (UV) irradiation were essential for the catalytic activity. However, Ph 2 CC1 2 was sufficient in catalytic amounts unlike the M(CO) 6---CC14-hv systems which require CC14 as solvent. A maximum was seen in catalytic activity at [Ph2CCl2]/[M]=0.5-2. The molecular weight of the poly(phenylacetylene) was higher than those for MCl"-based catalysts.KEY WORDS Metathesis Polymerization / Substituted Acetylene / Norbornene / Diphenyldichloromethane / Ultraviolet Irradiation / It is well known that ring-opening metathesis polymerization of cycloolefins is effected by various transition metal catalysts. 1 -3 Such catalysts include transition metal chloride-organometallic cocatalyst systems, 1 -3 metallacyclobutanes, 4 -6 Schrock-type metal carbenes, 7 ruthenium carbenes developed by Grubbs et al. 8 Groups 5 and 6 transition metal chloride-based catalysts,9 Schrock-type metal carbenes, 10 • 11 etc. are effective in metathesis polymerization of substituted acetylenes as well. Polymerization of phenylacetylene readily proceeds in the presence of metal chloride-based catalysts, but the molecular weight of the formed polymer is around 5000 at highest probably due to the Lewis acidity of the catalysts. 9 Group 6 transition metal hexacarbonyl-based catalysts, M(CO) 6 -CClchv (M = W, Mo), induce metathesis polymerization of both cycloolefins 12 · 13 and substituted acetylenes. 14 • 15 The Lewis acidity of these catalysts is lower than those of metal chlorides, and consequently the molecular weight of the poly(phenylacetylene) produced by the W(COkbased catalyst reaches almost a hundred thousand. A requirement for the M(C0) 6 -based catalysts is that CC1 4 must be used as solvent; otherwise sufficient catalytic activity is not attained. It is assumed that a metal carbene, which serves as active species, is generated by CO elimination from M(CO) 6 by ultraviolet (UV) irradiation and subsequent reactions of M(CO) 5 with CC1 4 , and so forth. 16 Further, generation of tungsten diphenylcarbene as an intermediate in the W(CO) 6 -Ph 2 CC1 2 -hv system was suggested on the basis of a finding that the presence of 2-ethoxynorbornene in this system leads to the formation of a diphenylcarbene adduct. 17 Taking this into account, we examined Ph 2 CCl 2 in place of CC14 in the W(CO) 6 -CC1 4 -hv system to find that the W(CO) 6 -Ph2CC12-hv system polymerizes phenylacetylene. 18 In the present study, we investigated the polymerization of substituted acetylenes and norbornene by the M(CO)6-Ph2CC12-hv (M = W, Mo) systems in detail to clarify the effectiveness of Ph 2 CC1 2 as second catalyst component 1 To whom all correspondence should be addressed. a...

Compelling mechanistic data and identification of the active species in tungsten-catalyzed alkyne polymerizations: conversion of a trianionic pincer into a new tetraanionic pincer-type ligand

“…Additionally, 2-t Bu polymerizes phenylacetylene and 1-decyne with catalytic activities up to 5.64 Â 10 6 g PPA mol À1 h À1 and 7.98 Â 10 6 g PA mol À1 h À1 , respectively. To the best of our knowledge, 2-t Bu is the most active phenylacetylene polymerization W-based catalyst, 28,29,[39][40][41][80][81][82][83][84][85][86][87][88][89] and more active than all known Mo-, [85][86][87][88][89][90] Rh-, 73,81,82,89,[91][92][93][94][95][96][97][98] Ir-, [98][99][100] and Pd-based catalysts. [101][102][103][104][105] Experiments were conducted to probe the mechanism of the acetylene polymerization by specically identifying the species that results from addition of one monomer unit to either 2-t Bu or 2-Ph.…”

Catalytic cyclopolymerization and copolymerization of 1,6-heptadiynes by Mo(CO)6

“…13 A unique feature of this finding is that intramolecular cyclopolymerization of ␣,-diynes catalyzed by simple Mo(CO) 6 under thermal conditions is unprecedented, although Mo(CO) 6 -based catalytic systems such as Mo(CO) 6 /Ph 2 CCl 2 /h and Mo(CO) 6 / C 6 H 5 OH/C 6 H 5 Cl have been known to be effective for intermolecular metathesis polymerization of phenylacetylene (PA) and norbornene. 14,15 Thus, we feel that this reaction should be extended to other 1,6-heptadiynes, as illustrated in Scheme 1, to investigate the general applicability of Mo(CO) 6 . In addition, the success of the highyield synthesis of poly(DEDPM) by Mo(CO) 6 encouraged us to attempt the synthesis of a copolymer containing both 1,6-heptadiynes and PA.…”

Καταλυτικός Πολυμερισμός Ακόρεστων Οργανικών Υποστρωμάτων Με Σύμπλοκες Ενώσεις Των Στοιχείων Μετάπτωσης

“…Η χρήση καταλυτικής ποσότητας Ph 2 CCl 2 καθιστά ικανή την παράλειψη του CCl 4 ως διαλύτη στον πολυμερισμό των ακετυλενίων με καρβονύλια των μετάλλων. Για παράδειγμα, ο πολυμερισμός του φαινυλακετυλενίου με [W(CO) 6 ] παρουσία Ph 2 CCl 2 σε τολουόλιο προχωρά ομογενώς με φωτοακτινοβόληση προς πολυμερές με M n περίπου 2×10 4[165,166]. Πολύ υψηλού μοριακού βάρους πολυμερή (M n > 10 5 ) λαμβάνονται από στερεοχημικά ογκώδη αρωματικά και αλειφατικά ακετυλένια.Άλλη μία επέκταση των καταλυτών [M(CO) 6 ] (M = Mo, W) είναι η χρήση καταλυτικής ποσότητας οξέωνLewis αντί του CCl 4[167], η οποία είναι επίσης γνωστή στη μετάθεση των ολεφινών.…”