5-Amino-3-imino-1,2,6,7-tetracyano-3H-pyrrolizine: synthesis of alkylimino derivatives. X-Ray crystal and molecular structures of the hex-5-enyl, and Langmuir-Blodgett .lm of the octyl and octadecyl derivatives

The alkylimino-substituted derivatives of 5-amino-3-imino-1,2,6,7-tetracyano-3H-pyrrolizine, H₂N- C₇N(CN)₄=NR, R=hex-5-enyl (1), octyl (2), octadecyl (3), have been synthesized through a nucleophilic substitution reaction on the amino group of the anion 2-(5-amino-3,4-dicyano-2H-pyrrol-2-ylidene)-1,1,2- tricyanoethanide, C₅N₃-C₄N(CN)₂-NH₂^-(L´). A sigmatropic rearrangement via a [1,5]-H shift is involved in this synthesis and also in the deprotonation of 1, leading to the anion C₅N₃-C₄N(CN)₂- NH(CH₂)₄CH=CH₂^-(1´) isolated as the tetraphenylarsonium salt, AsPh₄1´. All the new compounds have been characterized by elemental analysis and IR, UV-VIS and 1H NMR spectroscopy. The X-ray crystal and molecular structure of 1 has been determined. Langmuir-Blodgett (LB) films from 2 and 3 have been deposited and characterized by polarised optical absorption spectroscopy.