Cytosine nucleobase as a tridentate ligand: metal binding to N(3), N(4) and O(2) in trans-[(NH2Me)2Pt(dmcyt)2Ag2][NO3]2(dmcyt = 1,5-dimethylcytosinate)

Abstract

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Reactivity of Ammonia Ligands of the Antitumor Agent Cisplatin: A Unique Dodecanuclear Pt4,Pd4,Ag4 Platform for Four Cytosine Model Nucleobases

“…While Pt À N and Pd À N bond lengths agree with expectations, [14] both the Ag À O and Ag À N lengths are significantly longer than in a mixed Pt,Ag complex of 1,5-dimethylcytosine, [15] in which they amount to 2.259(8) and 2.16(1) (average), respectively. The binding of the Ag1 and Ag1' atoms is special in that all four of the surrounding d 8 metal ions, that is, Pd1, Pt1, Pt2, and Pd2 (for the case of Ag1), appear to be involved in weak donor!acceptor bond formation with the Ag (11) ) are longer than those in typical donor-acceptor bonds between such metals, [12b, 17, 18] yet the number (four) of such interactions is larger in the present case.…”

“…+ ion binding to the O2 position of N3,N4-metalated cytosine nucleobases has been observed before, [14,15] and the reversal of the chemical-shift changes upon addition of Cl À ions to a solution of 10 (see below) further supports this view.…”

“…These distances are in the range seen in related Pt,Ag complexes with www.chemeurj.org cytosinato and uracilato ligands. [15,19] Again, it could indicate weak donor!acceptor interactions between the Pt ions and the Ag + ion. Essentially, it would imply that all 4 Pt ions in 10 have undergone an extension of their coordination spheres from 4 to 4+2.…”

N1 and N3 Linkage Isomers of Neutral and Deprotonated Cytosine with trans-[(CH3NH2)2PtII]

“…X-ray structure of heteronuclear derivative 4 of the mixed tautomer compound trans-[Pt(CH 3 NH 2 ) 2 (C-N1)(C-N3)] (3 b): We have demonstrated in numerous cases that trans-[Pta 2 (1-MeC-N3)] 2 (a NH 3 or CH 3 NH 2 ) behaves as an excellent ligand for metal ions M, such as Pd II , [36] Cu II , [37] Ag I , [38] and Hg II , [16a, 16d] to produce heteronuclear complexes with the heterometal ions substituting protons of the exocyclic amino group. Strong dative Pt 3 M bonds are formed with the d 8 metal ion M Pd II and the d 9 metal ion M Cu II .…”

Nucleophilic behaviour of the neutral complexes [M(C ^ P)(S2CNMe2)] [M = Pd, Pt; C ^ P = CH2C6H4P(C6H4Me-o)2-κ-C,P ] towards Ag(I) and Au(I) compounds. Synthesis (M = Pd, Pt) and molecular structures (M = Pt) of polynuclear complexes containing M–Ag and M–S bonds

“…As far as we know, only a small number of Pt-Ag complexes involving neutral Pt() fragments have been described, 2-8 and structurally characterized. [4][5][6][7][8] In the latter complexes there are ligands bridging between the Pt and Ag atoms.…”