Platinum(II) and magnesium(II) nucleotide complexes. Synthesis, FT-ir spectra, and structural properties

Abstract

Guanosine-5′-monophosphate (5′-GMP) reacts with Pt(II) and Mg(II) metal ions to give complexes of the type Pt(5′-GMP)nCl2•xH2O, cis- and trans-[Pt(NH3)2(5′-GMP)2]Cl2•xH2O and Mg(5'-GMP2)•xH2O, where n = 1, 2, 3, 4 and x = 4–10.Spectroscopic and chemical evidence showed marked similarities with those of the structurally known N7-bonded 5′-GMP complexes of Mn(II), Co(II), Ni(II), Cu(II), and Cd(II) metal ions. Therefore, Pt(II) and Mg(II) are also found to be N7-bonded in these series of nucleotide complexes.The direct phosphate coordination was observed in Mg(II) nucleotide complexes obtained from acidic solution, whereas Mg(II) complexes prepared from neutral solution showed no direct phosphate–Mg(II) interaction. Pt(II) complexes exhibited no direct phosphate metal bonding, while the possibility of an indirect Pt(II)–phosphate interaction through a hydrogen-bonded water molecule can be proposed here.

A Fourier transform infrared study of the electrophilic attack at the N7-site of guanosine-5′-monophosphate

“…The effect of N7-protonation on the phosphate and sugar vibrations The ir spectra of the mononucleotide phosphate group has been reported earlier (20). The phosphate group of R O P O~~-moiety in 5'-GMPNa, shows five vibrational frequencies in the region 1100-350 cm-' (20,23).…”

“…The preparation of Pt2' and Mg" complexes was described earlier (20). The free 5'-GMP acid was used as N7-protonated and was recrystallized by the reported method (17).…”

An FT-ir study of cis study of trans-dichlorodiammineplatinum(II) bound to inosine-5′-monophosphate

“…The perturbation of the above vibrations is much stronger (Figs. 1-3 The absorption band with medium intensity at 1480 cm-' mainly related to the Cs-N7 stretching and C,-H bending vibrations (35) shifted to a higher frequency in the spectra of the complexes. The shift of this band (A3 = 5-20 cm-') towards higher frequencies is consistent with the C=Nf frequency.…”

“…Phosphate vibrational frequencies he vibrational frequencies of mononucleotides together with their metal-complexes have been discussed earlier (35). The ir spectra of 5'-IMPNa?…”

“…The IT-ir spectra of the structurally known (30, 43) [Cu(IMP).H20],, and [Zn-(IMP).H20], containing direct metal-phosphate bonding, showed shifting and splitting of these two bands, whereas the infrared spectra of the corresponding Co(I1) and Ni(I1) complexes (35) containing an indirect metal-phosphate interaction, through coordinated water molecules (44) exhibited no considerable changes in these vibrational frequencies.…”