| Abstract
| - The sulfur ligand was rapidly replaced by 5‘-GMP to produce [Pt(5‘-GMP-N7)(pyAc-N,O)(NH3)]+
- This paper reports on the chemistry of platinum complexes containing bidentate pyridine-carboxylate (pyAc =pyridin-2-yl-acetate and picEt = pyridine-2-ethylcarboxylate, ethylpicolinate) (N,O) ligands. The pyridine-2-acetateand ethylpicolinate ligands form six- and five-membered chelates, respectively, upon formation of the Pt−carboxylatebond. In all reactions with picEt with various platinum complex starting materials, spontaneous de-esterification ofthe pendant carboxylate ester occurs to give directly the chelates K[PtCl2(pic-N,O)]-trans-[Pt(pic-N,O)2] and SP-4,2-[PtCl(pic-N,O)(NH3)] without any evidence of intermediates. The de-esterification is solvent dependent, andmolecular modeling was used to explain this reaction. The reactions of the geometric isomers of [PtCl(pyAc-N,O)(NH3)] with 5‘-guanosine monophosphate, 5‘-GMP, and N-acetyl-l-methionine, AcMet, were investigated by NMRspectroscopy. The objective was to ascertain by model chemistry the feasibility of formation of ternary DNA−Pt−protein adducts in biology. Model nucleotide and peptide compounds were formed in situ by chloride displacementgiving [PtL(pyAc-N,O)(NH3)]+ (L = 5‘-GMP or AcMet). Competitive reactions were then examined by addition ofthe complementary ligand L. Sulfur displacement of coordinated 5‘-GMP was slow. For SP-4,3-[Pt(AcMet)(NH3)(PyAc-N,O)]+, a rapid displacement of the sulfur ligand by 5‘-GMP was observed, giving SP-4,2-[Pt(5‘-GMP-N7)(pyAc-N,O)(NH3)]+.
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