 The cyanate (cyanate ester) functional group (R−O−C≡N) is arranged differently from the isocyanate group (R−N=C=O).Isocyanides have the connectivity R−N≡C, lacking the oxygen of the cyanate groups.In terms of bonding, isocyanates are closely related to carbon dioxide (CO2) and carbodiimides (C(NR)2).