Isocyanides polymerisation

Polyisocyanides have a rigid helical structure with four monomeric units per helix turn [254,255]. The polymers of isocyanides do not display any stereoisomerism, since the carbon atoms in the polymer backbone are not chirotropic. However, it is worth noting that isocyanide polymerisation is stereoselective as regards the screw sense of the polymeric helix (atropisomerism). Therefore, right- and left-handed helices are formed from achiral isocyanides [256], When the monomer is achiral, a racemic mixture of right- and left-handed helices is obtained, e.g. in the case of the polymerisation of t-butylisocyanide [257,258]. When the alkyl... 

The molar heat of formation of this endothermic compound (+230-250 kJ, 4.5 kJ/g) is comparable with that of buten-3-yne (vinylacety lene). While no explosive decomposition of the isocyanide has been reported, the possibility should be borne in mind [1], It is stable at — 15°C, but isomerises to acrylonitrile and polymerises at ambient temperature [2],... 

Heterounsaturated monomers such as aldehydes, ketones, ketones, isocyanates and isocyanides, which have been reported to undergo a polymerisation in the presence of coordination catalysts, are listed in Table 9.3 [1,3]. 

Heterounsaturated monomers that undergo coordination polymerisation or copolymerisation with other monomers can be divided into two classes monomers with a carbene-like structure such as isocyanides and carbon monoxide which are coordinated by n complex formation with the transition metal atom at the catalyst active site, and monomers such as isocyanates, aldehydes, ketones and ketenes which are coordinated via 5-bond formation with the metal atom at the catalyst active site. 

Polymerisation of isocyanides, R—N=C, leads to polyisocyanides [poly(imino-methylene)s, poly(carboimidoyl)s] [254] ... 

Isocyanides. Several instances for nickel(ii) and palladium(ii) complexes have been suggested. - One interesting feature is that whereas carbon monoxide only inserts once into a given bond, isocyanides can insert repeatedly, providing a potential route for catalytic polymerisation. ... 

Multinuclear acetylide complexes containing two or three Pd-Pt p-ethynediyl units have been prepared and applied as multifunctional initiators for the living polymerisation of aryl isocyanides, giving two- or three-armed poly(isocyanide)s with a narrow polydispersity index. A similar Pd-Pt i-ethynediyl complex has been used an an initiator in the polymersation of aryl isocyanide bearing... 

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