913724-84-2Relevant academic research and scientific papers
Mono- and polynuclear complexes of the model nucleobase 1-methylcytosine. Synthesis and characterization of cis[(PMe2Ph)2Pt{1-MeCy(- H)}]3(NO3)3 and cis-[(PPh3) 2Pt{1-MeCy(-H)}(1-MeCy)]NO3
Longato, Bruno,Montagner, Diego,Zangrando, Ennio
, p. 8179 - 8187 (2006)
The hydroxo complex cis-[L2Pt(μ-OH)]2(NO 3)2 (L = PMe2Ph), in various solvents, reacts with 1-methylcytosine (1-MeCy) to give as the final product the cyclic species cis-[L2Pt{1-MeCy(-H),N3N4}]3(NO 3)3 (1) in high or quantitative yield. X-ray analysis of 1 evidences a trinuclear species with the NH2-deprotonated nucleobases bridging symmetrically the metal centers through the N3 and N4 donors. A multinuclear NMR study of the reaction in DMSO-d6 reveals the initial formation of the dinuclear species cis-[L2Pt{1-MeCy(-H),N 3N4}]22+ (2), which quantitatively converts into 1 following a first-order kinetic law (at 50°C, t 1/2 = 5 h). In chlorinated solvents, the deprotonation of the nucleobase affords as the major product (60-70%) the linkage isomer of 1, cis-[L2Pt{1-MeCy(-H)}]33+ (3), in which three cytosinate ligands bridge unsymmetrically three cis-L2Pt2+ units. In solution, 3 slowly converts quantitatively into the thermodynamically more stable isomer 1. No polynuclear adducts were obtained with the hydroxo complex stabilized by PPh3. cis-[(PPh3) 2Pt(μ-OH)]2(NO3)2 reacts with 1-MeCy, in DMSO or CH2Cl2, to give the mononuclear species cis-[(PPh3)2Pt{1-MeCy(-H)}(1-MeCy)](NO3) (4) containing one neutral and one NH2-deprotonated 1-MeCy molecule, coordinated to the same metal center at the N3 and N4 sites, respectively. X-ray analysis and NMR studies show an intramolecular H bond between the N4 amino group and the uncoordinated N3 atom of the two nucleobases.
