Trans-pyridine tetraammine complexes of Ru~(II) and Ru~(III) with N7-coordninated purine nucleosides

摘要

The synthesis, spectroscopic, and electrochemical properties of trans-[L(Pyr)(NH_3)_4Ru~(II/III)] (Pyr=py, 3-phpy, 4-phpy, 3-bnpy, or 4-bnpy; L=H_2O, Guo, dGuo, 1MeGuo, Gua, Ino, or G~7-DNA) are reported. As expected, the Pyr ligand slows DNA binding by trans-[(H_2O)(Pyr)(NH_3)_4Ru~(II)]~(2+) relative to [(H_2O)(NH_3)_5Ru~(II)]~(2+) and favors reduction of Ru~(III) by about 150 mV. The pyridine ligand also promotes the disproportionation of Ru~(III) to afford the corresponding complexes of Ru~(II) and, presumably, Ru~(IV). For L=Ino, disproportionation follows the rate law: d[Ru~(II)]/dt = k_0[Ru~(III)] + k_1[OH~-][Ru~(III)], k_0 = (2.7+-0.7) x 10~(-4) s~(-1) and k_1 = 70 +- 1 M~(-1) s~(-1).