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rrani-[RuCl(N02)(py)4] is oxidized chemically to give tmns-[RuCl(0)(py)4]+, while tmns-[Ru(N02)(H20)(py)4]+ yields the analogous ZraHi-[Ru(0N0)(0)(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-[RuCl(N02)(py)4] generates, at 25 °C, three species, Zranr-[RuCl (NO) (py)4]2+, írans-[RuCl(OH)(py)4]+, and iraní-[RuCl-(0)(py)4]+, while 1.25 mol of electrons are released per mole of iraní-[RuCl(N02)(py)4], At -40 °C, however, another route where an oxidation of Zrozzi-[RuCl(N02)(py)4] by 1.5 mol of electrons yields two species, iraní-[RuCI(NO)(py)4]2+ and trans-[RuCl(0N02)(py)4]+, seems to be operating. The above electrochemical results suggest that the chemical oxidation of iranj-[RuCl(N02)(py)4] proceeds via the formation of a transient intermediate consisting of iraní-[RuCl(N02)(py)4]+ and its isomer, trans-[RuCl(ONO)(py)4]+. The intermediate, |Cl(py)4Ru-N(0)0-N(0)0-Ru(py)4Cl)2+, then decomposes into írans-[RuCl(0)(py)4]+ and trans-[RuCl(NO)(py)4]2+, along with NOf ions. Under the chemical conditions, rrani-[RuCl-(NO)(py)4]2+, once formed, changes rapidly to trans-[RuCl(N02)(py)4], the original starting material of the reaction, and then follows repeated reoxidation until the oxo complex of Ru(IV), /rani-[RuCl(0)(py)4]+, is formed as a sole product. Such an intermediate process is not necessary for the chemical oxidation of /rani-[Ru(N02)(H20)(py)4]+, which gives iraní-[Ru-(0N0)(0)(py)4]+.

The electrochemical behavior of trans-[Ru(NO2)X(py)4]n(n = 0 for X = NO2 and n = + for NH3) in CH3CN was investigated at various temperatures. trans-[RuII(NO2)2(py)4] undergoes a one-electron oxidation to give trans-[RuIII(NO2)2(py)4]+. Rapid chemical reactions (nitro–nitrito isomerization, dimeric intermediate formation, and its disintegration) follow in succession until nearly equal amounts of trans-[Ru(NO)(NO2)(py)4]2+ and trans-[RuII(NO2)(solvent)(py)4]+ are generated as the final products. Essentially the same result was found in trans-[Ru(NO2)(NH3)(py)4]+. These results were quite different from those observed previously in the electrochemical oxidation of trans-[RuIICl(NO2)(py)4], where both trans-[RuIVCl(O)(py)4]+ and trans-[Ru(NO)Cl(py)4]2+ were generated directly by one-electron oxidation. We conclude that the different electrochemical behavior between trans-[RuCl(NO2)(py)4] and trans-[Ru(NO2)X(py)4]n (X = NO2 and NH3) stems primarily from a different disintegration mode of the above-mentioned dimeric intermediate species.