Rhodium-mediated stereoselective polymerization of "carbenes".
Unprecedented rhodium-catalyzed stereoselective polymerization of "carbenes" from ethyl diazoacetate (EDA) to give high molecular mass poly(ethyl 2-ylidene-acetate) is described. The mononuclear, neutral [(N,O-ligand)M(I)(cod)] (M = Rh, Ir) catalytic precursors for this reaction are characterized by (among others) single-crystal X-ray diffraction. These species mediate formation of a new type of polymers from EDA: carbon-chain polymers functionalized with a polar substituent at each carbon of the polymer backbone. The polymers are obtained as white powders with surprisingly sharp NMR resonances. Solution and solid state NMR data for these new polymers reveal a highly stereoregular polymer, with a high degree of crystallinity. The polymer is likely syndiotactic. Material properties are very different from those of atactic poly(diethyl fumarate) polymer obtained by radical polymerization of diethyl fumarate. Other diazoacetates are also polymerized. Further studies are underway to reveal possible applications of these new materials.
Hetterscheid
Dennis G H
DG
Institute for Molecules and Materials (IMM), Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.
Hendriksen
Coen
C
Dzik
Wojciech I
WI
Smits
Jan M M
JM
van Eck
Ernst R H
ER
Rowan
Alan E
AE
Busico
Vincenzo
V
Vacatello
Michele
M
Van Axel Castelli
Valeria
V
Segre
Annalaura
A
Jellema
Erica
E
Bloemberg
Tom G
TG
de Bruin
Bas
B