Spectroscopic studies of some Pd(II), Pt(II), Ag(I), and Au(III) complexes of 4,6-diamino-2-thiopyrimidine and 4,6-diamino-2-methylthiopyrimidine. Structure and binding site determination

Abstract

Interaction of Pd(II), Pt(II), Ag(I), and Au(III) with 4,6-diamino-2-thiopyrimidine (DATP) and 4,6-diamino-2-methyl-thiopyrimidine (DAMTP) in aqueous medium resulted in the formation of new complexes which have been characterized by elemental analysis, ir, 1H-nmr spectroscopic techniques, magnetic susceptibility measurements in the solid state, and conductivity measurements in DMF solution. The ir and 1H-nmr spectra were consistent with coordination involving the non-protonated ring nitrogen atom, the exocyclic sulphur atom, or N,S-chelation.

Biologically active 2-thione-4,6-diamino-5-hydroxypyrimidine transition metal complexes

“…This indicates that HTDAHP acts as a bidentate ligand, chelating the metal ion through the deprotonated hydroxy and amino N(6)H 2 groups, without any participation of the thione sulphur or cyclic nitrogen atoms in coordination [16]. This feature is further supported by the observation of a band near 1178 cm -1 arising from the m(C=S) stretch, which remains unchanged [20]. wave number with the existence of m s (NH 2 ), m as (NH 2 ) and m(OH) stretches more or less in the same position as in the free ligand [26].…”

“…The spectrum of HTDAHP supports the preponderance of the thione form in the solid phase (Scheme 1). This is due to the presence of the m(NH) stretch at 2970 cm -1 [14], the absence of m(SH) near 2600 cm -1 and the formation of the characteristic thioamide bands due to extensive coupling of d(NH), m(C=N), m(NCS) and m(C=S) at 1652, 1562, 1455 and (1375, 1268, 1177) cm -1 , respectively [20][21][22]. The presence of m(C=C) + m(C=N) stretches near 1560 cm -1 is attributed to strong non-aromatic character [23].…”

Synthesis, Spectroscopic, and Anticancerous Properties of Mixed Ligand Palladium(II) and Silver(I) Complexes with 4,6-Diamino-5-hydroxy-2-mercaptopyrimidine and 2,2′-Bipyridyl

“…This suggests that Hdahmp acts as a mononegative bidentate ligand, coordinating the metal ion through the deprotonated hydroxyl and amino N(6)H 2 groups, without any participation of the thione sulfur or cyclic nitrogen atoms in coordination [23]. This feature is further supported by the observation that a band near 1178 cm −1 arises from ν (C=S) stretch that remains unchanged [18] (Scheme 2). The vibrational spectrum of [Ag(bpy)(Hdahmp)]NO 3 suggests the participation of the thione sulphur and the cyclic N(3) in coordination due to the shift observed in the ν (C=S) and ν (N–C=S) stretching vibrations (Scheme 3).…”

“…The vibrational spectrum of [Ag(bpy)(Hdahmp)]NO 3 suggests the participation of the thione sulphur and the cyclic N(3) in coordination due to the shift observed in the ν (C=S) and ν (N–C=S) stretching vibrations ( Scheme 3 ). This suggestion is supported by the slight shift of ν (NH) and δ (NH) to lower wave number with the existence of ν s (NH 2 ), ν as (NH 2 ), and ν (OH) stretches more or less in the same position as in the free ligand [ 18 , 22 , 24 ].…”

“…The spectrum of Hdahmp supports the existence of the thione form in the solid phase (Scheme 1). This can be attributed to the presence of ν (NH) stretch at 2970 cm −1 [17], the absence of ν (SH) near 2600 cm −1 , and the production of the characteristic thioamide bands due to extensive coupling of δ (NH), ν (C=N), ν (NCS), and ν (C=S) at 1652, 1562, 1455, and (1375, 1268, 1177) cm −1 , respectively [18–20]. …”