Two bis(amido)ruthenium(IV) complexes, [Ru(IV)(bpy)(L-H)(2)](2+) and [Ru(IV)(L)(L-H)(2)](2+) (bpy = 2,2'-bipyridine, L = 2,3-diamino-2,3-dimethylbutane, L-H = (H(2)NCMe(2)CMe(2)NH)(-)), were prepared by chemical oxidation of [Ru(II)(bpy)(L)(2)](2+) and the reaction of [(n-Bu)(4)N][Ru(VI)NCl(4)] with L, respectively. The structures of [Ru(bpy)(L-H)(2)][ZnBr(4)].CH(3)CN and [Ru(L)(L-H)(2)]Cl(2).2H(2)O were determined by X-ray crystal analysis. [Ru(bpy)(L-H)(2)][ZnBr(4)].CH(3)CN crystallizes in the monoclinic space group P2(1)/n with a = 12.597(2) Å, b = 15.909(2) Å, c = 16.785(2) Å, beta = 91.74(1) degrees, and Z = 4. [Ru(L)(L-H)(2)]Cl(2).2H(2)O crystallizes in the tetragonal space group I4(1)/a with a = 31.892(6) Å, c = 10.819(3) Å, and Z = 16. In both complexes, the two Ru-N(amide) bonds are cis to each other with bond distances ranging from 1.835(7) to 1.856(7) Å. The N(amide)-Ru-N(amide) angles are about 110 degrees. The two Ru(IV) complexes are diamagnetic, and the chemical shifts of the amide protons occur at around 13 ppm. Both complexes display reversible metal-amide/metal-amine redox couples in aqueous solution with a pyrolytic graphite electrode. Depending on the pH of the media, reversible/quasireversible 1e(-)-2H(+) Ru(IV)-amide/Ru(III)-amine and 2e(-)-2H(+) Ru(IV)-amide/Ru(II)-amine redox couples have been observed. At pH = 1.0, the E degrees is 0.46 V for [Ru(IV)(bpy)(L-H)(2)](2+)/[Ru(III)(bpy)(L)(2)](3+) and 0.29 V vs SCE for [Ru(IV)(L)(L-H)(2)](2+)/[Ru(III)(L)(3)](3+). The difference in the E degrees values for the two Ru(IV)-amide complexes has been attributed to the fact that the chelating saturated diamine ligand is a better sigma-donor than 2,2'-bipyridine.

A reversible three-proton three-electron couple has been observed for the electrochemical oxidation of cis-[Ru( b ~y ) ~( L ) ] 2 + (L = 2,3-dimethyl-2,3-diaminobutane) in aqueous acidic solution; controlled-potential electrochemical oxidation of cis-[R~(bpy)~(L)]2+ led to C-C bond cleavage in L and formation of cis-[Ru( b ~y ) ~( N H = c M e ~) ~] * + whose structure has been determined by X-ray crystallography.

Oxidation of [ R U ~~( ~~~) ~( N H ~C M ~~C M ~~N H ~) ~~+ by Celv in H20 generates the highly reactive cis-b i s ( i m i d o ruth e n i u m (vi 1 i n t e r m ed i ate , w h i c h re acts with H 0 to g ive [ R u 11 ( b py ) ( 0 N C M e2 C M e2 N 0 ) 12+, t h e structure of which has been determined by X-ray crystallography.

[(n-Bu)4N][RuNCl4] reacts with 2,5-dimethyl-2,5-hexanediamine (L) in acetone to give a cationic dimeric RuVI⋮N complex [(RuVI(L)2N)2(μ-O)]Cl4 (1). The X-ray crystal structure of 1·H2O has been determined. The structure of 1 shows two Ru⋮N units bridged by a μ-oxo ligand. The Ru⋮N and Ru−O bond distances are 1.66(1) and 1.9896(8) Å, respectively.

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