Polymerisation of Isocyanides

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

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 

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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... 

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]. 

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