Normal internal coordinates, Force fields and vibrational study of
Species Derived from Antiviral adamantadine
Abstract
Complete vibrational assignments have been performed for free base,
cationic and hydrochloride species derived from antiviral adamantadine
by combination of hybrid B3LYP with the 6-31G* and 6-311++G** basis sets
and the SQMFF methodology. Normal internal coordinates and scaling
factors were used to obtain the harmonic force fields and scaled force
constants of three species in gas phase and in aqueous solution. Bond
lengths and angles of cationic and hydrochloride species show very good
concordances with the experimental of amantadinium azide. The cationic
species reveals higher solvation energy value, as compared with
antiviral agents, however, brincidofovir, the antiviral used to ebola
disease presents a higher reactivity against to adamantadine. Positive
value of Mulliken charge on N1 of hydrochloride species in solution
could justify the ionic character of H29•••Cl30 bond, as evidenced by
bond order and AIM calculations. The hydrochloride species is the most
reactive in both media while the cationic species the less reactive.
High electrophilicity and nucleophilicity indexes of cationic species in
both media justify its higher hydration. Good concordances were observed
between experimental and predicted 1H and 13C NMR and electronic
spectra. In solution, the three species are present as revealed by the
experimental UV spectrum of hydrochloride amantadine