Abstract:The bis(tosylimido)osmium(VI) porphyrins [Os(VI)(Por)(NTs)(2)] [Por = tetraphenylporphyrinato (TPP), meso-tetrakis(p-tolyl)porphyrinato (TTP), meso-tetrakis(4-chlorophenyl)porphyrinato (4-Cl-TPP), meso-tetrakis(4-methoxyphenyl)porphyrinato (4-MeO-TPP); Ts = tosyl] were prepared from the reactions of [Os(II)(Por)(CO)(MeOH)] with excess PhI=NTs in dichloromethane. The X-ray crystal structure of [Os(VI)(TPP)(NTs)(2)] has been determined. Crystal data for [Os(VI)(TPP)(NTs)(2)]: triclinic, space group P&onemacr; (N… Show more
“…In all cases the integration ratios are consistent with the bis(tosylimido) formulation of complexes 2 . Furthermore, the whole spectrum of each of 2a − d is extremely similar to that of [Os VI (Por)(NTs) 2 ] with the same porphyrinato ligand (the structure of [Os VI (TPP)(NTs) 2 ] has been determined by X-ray crystallographic study 30 ). 1 …”
Section: Resultsmentioning
confidence: 81%
“…However, while the latter conversion appreciably blue shifts the β band, an obvious red shift of this band occurs in the case of the former conversion. On the other hand, the spectra of 2 are considerably different from their osmium analogues, [Os VI (Por)(NTs) 2 ] . This is not surprising, since there is also a large difference between the spectra of [Ru VI (Por)O 2 ] and [Os VI (Por)O 2 ] …”
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 (PhINTs) 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.
“…In all cases the integration ratios are consistent with the bis(tosylimido) formulation of complexes 2 . Furthermore, the whole spectrum of each of 2a − d is extremely similar to that of [Os VI (Por)(NTs) 2 ] with the same porphyrinato ligand (the structure of [Os VI (TPP)(NTs) 2 ] has been determined by X-ray crystallographic study 30 ). 1 …”
Section: Resultsmentioning
confidence: 81%
“…However, while the latter conversion appreciably blue shifts the β band, an obvious red shift of this band occurs in the case of the former conversion. On the other hand, the spectra of 2 are considerably different from their osmium analogues, [Os VI (Por)(NTs) 2 ] . This is not surprising, since there is also a large difference between the spectra of [Ru VI (Por)O 2 ] and [Os VI (Por)O 2 ] …”
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 (PhINTs) 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.
“…We previously reported the X‐ray crystal structures of bis(sulfonylimide)osmium(VI) porphyrins [Os VI (NTs) 2 (tpp)]15g and [Os VI (NTs) 2 (F 20 ‐tpp)] 15j. The two osmium sulfonylimide complexes are not reactive toward alkene aziridination and CH bond amination reactions and they show OsN distances of 1.795(4)–1.804(4) Å and OsNS angles of 154.4(2)–168.3(2)°, which are comparable to the RuN distance (1.79(3) Å) and RuNS angle (162.5(3)°), respectively, in [Ru VI (NMs) 2 (tmp)].…”
The X-ray crystal structure of [Ru(VI) (NMs)2 (tmp)] (Ms=SO2 - p-MeOC6 H4 ; tmp=5,10,15,20-tetramesitylporphyrinato(2-)), a metal sulfonylimide complex that can undergo alkene aziridination and C-H bond amination reactions, shows a Ru=N distance of 1.79(3) Å and Ru-N-S angle of 162.5(3)°. Density functional theory (DFT) calculations on the electronic structures of [Ru(VI) (NMs)2 (tmp)] and model complex [Ru(VI) (NMs)2 (por(0) )] (por(0) =unsubstituted porphyrinato(2-)) using the M06L functional gave results in agreement with experimental observations. For the amination of ethylbenzene by the singlet ground state of [Ru(VI) (NMs)2 (por(0))], DFT calculations using the M06L functional revealed an effectively concerted pathway involving rate-limiting hydrogen atom abstraction without a distinct radical rebound step. The substituent effect on the amination reactivity of ethylbenzene by [Ru(VI) (NX)2 (por(0) )] (X=SO2 -p-YC6 H4 with Y=MeO, Me, H, Cl, NO2 ) was examined. Electron-withdrawing Y groups lower the energy of the LUMOs of [Ru(VI) (NX)2 (por(0))], thus facilitating their interaction with the low-lying HOMO of the ethylbenzene C-H bond and hence increasing the reactivity of [Ru(VI) (NX)2 (por(0) )]. DFT calculations on the amination/aziridination reactions of [Ru(VI) (NSO2 C6 H5 )2 (por(0) )] with pent-4-enal, an aldehyde substrate bearing acyl, homoallylic, and allylic C-H bonds and a C=C bond, revealed a lower reaction barrier for the amination of the acyl C-H bond than for both the amination of the other C-H bonds and aziridination of the C=C bond in this substrate.
“…The reaction of PhINTs with complexes of ruthenium(II), 87 osmium(II), 143,144 and cobalt(III) 145 results in the imidation at the metal center with the formation of the respective tosylimidometal complexes. X-Ray crystal structures were determined for several bis(tosylimido)ruthenium(VI) and bis(tosylimido)osmium(VI) porphyrin complexes.…”
Section: Scheme 17mentioning
confidence: 99%
“…X-Ray crystal structures were determined for several bis(tosylimido)ruthenium(VI) and bis(tosylimido)osmium(VI) porphyrin complexes. 87,143,144 The reactivity of a cobalt(II) iminoiodane complex in hydrogen atom abstraction reactions has been investigated by Kundu and coauthors. 146 The in situ generated aziridine products can be easily transformed to heterocyclic compounds.…”
Iodonium imides (ArINR) represent an important class of hypervalent iodine(III) compounds recently emerging as versatile, efficient and environmentally friendly synthetic reagents with numerous applications in academic and industrial research. Iodonium imides, which are also known as iminoiodanes, are widely used in organic synthesis as common nitrene precursors in the aziridination of alkenes and the amidation reactions of various organic substrates. In the present review, the preparation and structural features of iminoiodanes are discussed, and recent developments in their synthetic applications are summarized.
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