Infrared spectroscopic investigation of the formation of adducts of Fe-phthalocyanine with hydrazine and ammonia

Abstract

The predominant effect of the interaction of hydrazine (N₂H₄) with metal phthalocyanines (MPcs) is catalytic decomposition of N₂H₄ forming NH₃ and N₂. With FePc, in parallel, both physisorption and adduct formation, the latter involving the total bulk of FePc, can be observed by i.r. spectroscopy. The FePc–N₂H₄ adduct is formed with α-FePc and β-FePc as well. The reaction rate is several orders of magnitude higher in the reaction with α-FePc; in vacuum at temperatures below 450 K, the adduct decomposes reforming α-FePc. Hence, the adduct resembles the structure of α-FePc rather than that of β-FePc. The adduct between FePc and NH₃ is formed starting from β-FePc only; it decomposes in vacuum to β-FePc, even at temperatures well below the temperature of the α–β transition. Hence, the structure of FePc–NH₃ resembles more the structure of β-FePc.