Bis(tosylimido)ruthenium(VI) porphyrins, [RuVI(Por)(NTs)2] (Por = TPP, TTP, 4-Cl-TPP, 4-MeO-TPP, OEP), were prepared in 60−74% yields by treatment of [RuII(Por)(CO)(MeOH)] with (N-(p-tolylsulfonyl)imino)phenyliodinane (PhINTs) in dichloromethane. In dichloromethane containing pyrazole, they reacted with alkenes or alkanes to give tosylamidoruthenium(IV) porphyrins, [RuIV(Por)(NHTs)(pz)], in about 75% yields. The reactions of [RuVI(TPP)(NTs)2] and [RuVI(OEP)(NTs)2] with styrene, para-substituted styrenes, norbornene, cyclooctene, and β-methylstyrene afforded the corresponding N-tosylaziridines in 66−85% yields. The aziridination of cis-stilbene and cis-β-methylstyrene by [RuVI(Por)(NTs)2] is nonstereospecific with a partial loss of the alkene stereochemistry. Kinetic studies on the reactions between [RuVI(TPP)(NTs)2] and 16 alkenes (cyclooctene, norbornene, 2,3-dimethyl-2-butene, styrene, para-substituted styrenes, α- and β-methylstyrene, and α- and β-deuteriostyrene) gave the second-order rate constants (k 2) ranging from (1.60 ± 0.06) × 10 - 3 to (90 ± 4) × 10 - 3 dm3 mol - 1 s - 1 at 298 K. The slope of the linear plot of log k 2 vs E 1/2 for eight representative alkenes was found to be −1.7 V - 1. In the case of para-substituted styrenes, linear correlation between log k R (k R = relative rate) and σ+ gives a ρ+ value as small as −1.1. However, the effect of para substituents on k R can be best accounted for by considering both the polar and spin delocalization effect. Measurements on the secondary deuterium isotope effect revealed that only the β-carbon atom of styrene experienced a significant change in its hybridization in reaching the transition state. All these are consistent with rate-determining formation of a carboradical intermediate. The reactions of [RuVI(TPP)(NTs)2] and [RuVI(OEP)(NTs)2] with adamantane, cyclohexene, ethylbenzene, and cumene resulted in tosylamidation of these hydrocarbons and afforded the corresponding amides in 52−88% yields. For cyclohexane and toluene, the tosylamidation products were formed in poor yields (ca. 10%). Kinetic studies on the reactions between [RuVI(TPP)(NTs)2] and nine hydrocarbons (cumene, ethylbenzene, cyclohexene, and para-substituted ethylbenzenes) gave the second-order rate constants (k 2) in the range of (0.330 ± 0.008) × 10-3 to (16.5 ± 0.3) × 10-3 dm3 mol-1 s-1. These reactions exhibit a large primary deuterium isotope effect, with a k H/k D ratio of 11 for the tosylamidation of ethylbenzene. In the case of para-substituted ethylbenzenes, both electron-donating and -withdrawing substituents moderately promote the reaction. There is an excellent linear correlation between log k R and a related carboradical parameter. On the basis of these observations, a mechanism involving the rate-limiting formation of a carboradical intermediate is postulated.

An operationally simple method based on [Cn*RuIII(CF3CO2)3·H2O] (Cn* = N,N‘,N‘‘-trimethyl-1,4,7-triazacyclononane) catalyst and 1−1.2 equiv of tert-butyl hydroperoxide as terminal oxidant is effective for selective transformation of alcohols to aldehydes and ketones in methylene chloride. The reaction proceeds in high yield and selectivity. Preparation of benzaldehyde (98% yield) from benzyl alcohol on a 200 mmol scale can be performed without modification of the procedure such as slow addition of the oxidant or cooling to 0 °C, and catalyst turnovers of 700 are achieved. Oxidation of geraniol which contains an isolated trisubstituted CC bond leads to geranial selectively without oxidation of the CC bond. Results from Hammett correlation studies (ρ = −0.47) and primary kinetic isotope effect (k H/k D = 4.8) for the catalytic benzyl alcohol oxidations are inconsistent with an oxoruthenium (ORu) based mechanism. A mechanism involving reactive tBuO•/tBuOO• radicals is also excluded based on results from previous works:  Cheng, W.-C.; Fung, W.-H.; Che, C.-M. J. Mol. Catal. (A) 1996, 113, 311; absence of di-tert-butyl peroxide; and using cumyl hydroperoxide as a radical probe. A tert-butylperoxoruthenium complex is postulated to be the active intermediate.

The oxoruthenium(IV) complexes [RuIV(terpy)(6,6‘-Cl2-bpy)O](ClO4)2 (1a; terpy = 2,2‘:6‘,2‘ ‘-terpyridine; 6,6‘-Cl2-bpy = 6,6‘-dichloro-2,2‘-bipyridine), [RuIV(terpy)(tmeda)O](ClO4)2 (1b; tmeda = N,N,N‘,N‘-tetramethylethylenediamine), [RuIV(Cn)(bpy)O](ClO4)2 (1c; Cn = 1,4,7-trimethyl-1,4,7-triazacyclononane), and [RuIV(PPz*)(bpy)O](ClO4)2 (1d; PPz* = 2,6-bis[(4S,7R)-7,8,8-trimethyl-4,5,6,7-tetrahydro-4,7-methanoindazol-2-yl]pyridine) are effective for the epoxidation of aromatic alkenes in acetonitrile at ambient conditions. Their reactions with cis-alkenes such as cis-β-methylstyrene and cis-β-deuteriostyrene afford epoxides nonstereospecifically. The observation of the inverse secondary kinetic isotope effect for the β-d 2-styrene oxidations [k H/k D = 0.87 (1b), 0.86 (1d)], but not for α-deuteriostyrene (k H/k D = 0.98 for 1b and 1d), indicates that C−O bond formation is more advanced at the β-carbon atom than at the α carbon, i.e., a stepwise mechanism. The second-order rate constants (k 2) for the styrene oxidations are weakly dependent on the E°(RuIV/III) values of the oxoruthenium(IV) complexes, and both electron-withdrawing and -donating para substituents mildly accelerate the oxidation reaction of styrene. These findings discount strongly the intermediaries of an alkene-derived cation radical and a carbocation. A linear free-energy relationship between the second-order rate constants for the para-substituted styrene oxidations and the total substituent effect (TE) parameters has been established:  ρTE • = +0.43 (R = 0.99) for 1b, +0.50 (R = 0.98) for 1c, and +0.37 (R = 0.99) for 1d (Wu, Y.-D.; Wong, C.-L.; Chan, K. W.; Ji, G.-Z.; Jiang, X.-K. J. Org. Chem. 1996, 61, 746). This suggests that the oxidation of aromatic alkenes by oxoruthenium(IV) complexes should proceed via the rate-limiting formation of a benzylic radical intermediate. Oxidation of styrene and cis- and trans-β-methylstyrenes by the chiral oxoruthenium(IV) complex 1d attains moderate enantioselectivities, in which the production of cis-epoxide is more enantioselective than the trans counterpart. The ligand dissymmetry of PPz* together with the bipyridine ligand create a “chiral pocket” around the RuIVO moiety, leading to enantiofacial discrimination through nonbonding interaction. Because the acyclic benzylic radical intermediate would undergo cis−trans isomerization before the second C−O bond formation, the overall product enantioselectivity (% eeobs) cannot be determined exclusively by facial selectivity (eefacial) of the first irreversible C−O bond formation step. The extent of the isomerization, measured by the cis−trans-epoxide selectivity or diastereoselectivity of epoxide ring closure, is an important element in controlling the enantiomeric excess of the epoxides.

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A new chiral monooxoruthenium(iv) complex containing 2,6-bis 8,5,6,pyridine and 2,2'-bipyridine ligands is prepared and the X-ray crystal structure of its Ru"--OH2 precusor determined; this RuiV=O complex catalyses epoxidation of unfunctionalized alkenes with prom isi ng ena nt i oselectivity.