SELECTIVE FORMATION OF RUTHENIUM(IV) COMPLEXES WITH A MONOOXYGEN LIGAND - TRANS-[RUCL(O)(PY)4]+, [RUONO(PY)4]+

trans-[RuCl(NO2)(py)4] is oxidized chemically to give trans-[RuCl(O)(py)4]+, while trans-[Ru(NO2)(H2O)(py)4]+yields the analogous trans-[Ru(ONO)(O)(py)4]+with retention of the nitro nitrogen. The origins of the oxygen ligand in each complex clearly differ. Electrochemical oxidation was also utilized to investigate the following chemical reaction processes: trans-[RuCI(NO2)(py)4] generates, at 25 °C, three species, trans-[RuCl(NO)(py)4 2+, trans-[RuCl(OH)(py)4]+, and trans-[RuCl-(O)(py)4]+, while 1.25 mol of electrons are released per mole of trans-[RuCl(NO2)(py)4]. At -40 °C, however, another route where an oxidation of trans-[RuCl(NO2)(py)4] by 1.5 mol of electrons yields two species, trans-[RuCl(NO)(py)4]2+and trans-[RuCl(ONO2)(py)4]+, seems to be operating. The above electrochemical results suggest that the chemical oxidation of trans-[RuCl(NO2)(py)4] proceeds via the formation of a transient intermediate consisting of trans-[RuCl(NO2)(py)4]+and its isomer, trans-[RuCl(ONO)(py)4]+. The intermediate, {Cl(py)4Ru-N(O)O-N(O)O-Ru(py)4Cl}2 2+, then decomposes into trans-[RuCl(O)(py)4]+and trans-[RuCl(NO)(py)4]2+, along with NO2 -ions. Under the chemical conditions, trans-[RuCl-(NO)(py4]2+, once formed, changes rapidly to trans-[RuCl(NO2)(py)4], the original starting material of the reaction, and then follows repeated reoxidation until the oxo complex of Ru(IV), trans-[RuCl(O)(py)4]+, is formed as a sole product. Such an intermediate process is not necessary for the chemical oxidation of trans-[R(NO2)(H2O(py)4]+, which gives trans-[Ru-(ONO)(O)(py)4]+. © 1990, American Chemical Society. All rights reserved.