Abstract
Interactions of some aminopyrimidines, as electron donors, with the σ-acceptor, iodine, have led to the formation of CT complexes having the stoichiometric ratio 2:2 (donor (P):acceptor(I
2)), or formally 1:1. Thus, the well known triiodide complex, P
+I.I
3
−, resulting in situ, is a new acceptor that interacts with another molecule of the donor (P) to form a CT complex having the form, (P).(P
+I.I
3
−). Spectral tracking of these interactions have shown the stepwise formation of the triiodide CT complex.
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Interactions of some pyrimidine derivatives, 4-amino-2,6-dimethylpyrimidine, kyanmethin, (4AP), 2-amino-4,6-dimethylpyrimidine (2AP), 2-aminopyrimidine (AP), 2-amino-4-methylpyrimidine (AMP), 2-amino-4-methoxy-6-methylpyrimidine (AMMP), and 4-amino-5-chloro-2,6-dimethylpyrimidine (ACDP) as electron donors, with iodine (I
2), as a typical σ-electron acceptor, have been studied. Electronic absorption spectra of these interactions in several organic solvents of different polarities have performed instant appearance of clear charge transfer (CT) bands. Formation constants (
K
CT), molar absorption coefficients (
ɛ
CT) and thermodynamic properties, Δ
H, Δ
S, and Δ
G, of these interactions have been determined and discussed. Electronic absorption spectra of the solutions of the synthesized pyrimidines–iodine, P–I
2, CT complexes have shown the characteristic bands of the triiodide ion, I
3
−. UV/vis spectral tracking of these interactions have shown that by lapse of time the first formed CT complex, P–I
2, is transformed to the corresponding triiodide complex, P
+I.I
3
−, then, the later interacts as a new unconventional acceptor and it forms a CT complex of the form (P).(P
+I.I
3
−). Elemental analyses of these solid complexes have indicated the stoichiometric ratio 2:2, or formally 1:1, P:I
2.