Vinyl polymerization. 284. Polymerization of methyl methacrylate initiated by 4.4′‐diazidoazobenzene

Doiuchi, Tooru; Nakaya, Tadao; Imoto, Minoru

doi:10.1002/macp.1972.021610116

Cited by 1 publication

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References 17 publications

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“…CCDC 1575834 (3), 1443595 (12), 1575835 (13), 1575836 (14a), 1575837 (15) and 1575838 (41) contain the crystallographic data of the complexes shown in the paper; CCDC 1575459 (4), 1575460 (8) and 1575461 (17) contain the crystallographic data of the complexes shown below (SI only): bis(4-methoxyphenyl)diazomethane (5a), 3 bis(4-(dimethylamino)phenyl)diazomethane (5b), 4 methyl 2-diazo-2-(4-methoxyphenyl)acetate (6a), 5 methyl 2-diazo-2-phenylacetate (6b), 5 methyl 4-(1-diazo-2-ethoxy-2-oxoethyl)benzoate (6c), 6 9-diazo-9H-fluorene, 7 (Z)-1,2-diphenyldiazene (Z-16), 8 (E)-1,2bis(4-methoxyphenyl)diazene, 9 (E)-1,2-bis(4-fluorophenyl)diazene, 9 (E)-1,2-bis(4-(trifluoromethyl)phenyl)diazene, 10 (E)-1,2-bis(3,5-dimethylphenyl)diazene, 9,11 (E)-1,2-di-p-tolyldiazene, 9 dioctyl 4,4'-(diazene-1,2-diyl)(E)-dibenzoate, 12 (E)-1,2-bis(2,6-dimethylphenyl)diazene, 13 (E)-1,2-bis(3methoxyphenyl)diazene, 9,10 (E)-1-(p-tolyl)-2-(4-(trifluoromethyl)phenyl)diazene, 14 (E)-1,2-di-o-tolyldiazene, 9 (E)-1,1'-(diazene-1,2-diylbis(3,1-phenylene))bis(ethan-1-one), 9,15 (E)-1,2-bis(4-azidophenyl)diazene 16 . matched the previously reported values.…”

Section: Additional Crystallographic Informationmentioning

confidence: 99%

Structure and Reactivity of Half-Sandwich Rh(+3) and Ir(+3) Carbene Complexes. Catalytic Metathesis of Azobenzene Derivatives

et al. 2018

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Traditional rhodium carbene chemistry relies on the controlled decomposition of diazo derivatives with [Rh(OAc)] or related dinuclear Rh(+2) complexes, whereas the use of other rhodium sources is much less developed. It is now shown that half-sandwich carbene species derived from [Cp*MX] (M = Rh, Ir; X = Cl, Br, I, Cp* = pentamethylcyclopentadienyl) also exhibit favorable application profiles. Interestingly, the anionic ligand X proved to be a critical determinant of reactivity in the case of cyclopropanation, epoxide formation and the previously unknown catalytic metathesis of azobenzene derivatives, whereas the nature of X does not play any significant role in -OH insertion reactions. This perplexing disparity can be explained on the basis of spectral and crystallographic data of a representative set of carbene complexes of this type, which could be isolated despite their pronounced electrophilicity. Specifically, the donor/acceptor carbene 10a derived from ArC(═N)COOMe and [Cp*RhCl] undergoes spontaneous 1,2-migratory insertion of the emerging carbene unit into the Rh-Cl bond with formation of the C-metalated rhodium enolate 11. In contrast, the analogous complexes 10b,c derived from [Cp*RhX] (X = Br, I) as well as the iridium species 13 and 14 derived from [Cp*IrCl] are sufficiently stable and allow true carbene reactivity to be harnessed. These complexes are competent intermediates for the catalytic metathesis of azobenzene derivatives, which provides access to α-imino esters that would be difficult to make otherwise. Rather than involving metal nitrenes, the reaction proceeds via aza-ylides that evolve into diaziridines; a metastable compound of this type has been fully characterized.

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