1003605-45-5Relevant articles and documents
Photochemical cis-trans isomerization of cis-(η6-1,2- diphenylethene)Cr(CO)3 and the molecular structure of trans-(η6-1,2-diphenylethene)Cr(CO)3
Coleman, Anthony,Draper, Sylvia M.,Long, Conor,Pryce, Mary T.
, p. 4128 - 4134 (2007)
Visible irradiation of cis-(η6-1,2-diphenylethene)Cr(CO) 3 results in an efficient conversion to the trans isomer as confirmed by NMR, room-temperature UV-vis spectroscopy, and low-temperature matrix isolation studies. Laser flash photolysis of trans-(η6-1,2- diphenylethene)Cr(CO)3 at 355 nm forms a solvated dicarbonyl species, (η6-1,2-diphenylethene)Cr(CO)2. Matrix isolation studies confirm that cis to trans isomerization occurs under low-energy irradiation (γexc > 400 nm), while photolysis with γexc = 313 nm is required to induce CO loss. Time-dependent density functional theory (TDDFT) calculations predict wavelength-dependent photochemical cis to trans isomerization for low-energy (γexc: > 400 nm) irradiation, while high-energy irradiation (γexc > 300 nm) populates excited states that are labile to CO loss.
η6-Chromiumtricarbonyl complexes of stilbene and 4,4'-dimethoxystilbene: slipping off the ligands enables cis-trans isomerization
Todres, Z. V.,Ionina, E. A.
, p. 193 - 195 (1993)
η6-Chromiumtricarbonyl complexes of stilbene and 4,4'-dimethoxystilbene (both in the cis form as ligands) were prepared.The complexes are stable as dry solids, but disintegrate during exposure at 25 deg C in argon, with liberation of the ligands.They are returned as a mixture of cis-trans isomers.The conversion of cis-trans types observed depends not on the spontaneous isomerization of a ligand in a complex, but on the interaction between the slipping ligand and chromium sesquioxide - the product of the transformation of the Cr(CO)3 fragment.
Organometallic clusters with face-capping arene ligands. 4. Tris(cyclopentadienylcobalt) clusters with μ3-alkenyl- and μ3-alkylbenzenes
Wadepohl, Hubert,Büchner, Klaus,Herrmann, Michael,Pritzkow, Hans
, p. 861 - 871 (2008/10/08)
The (CpCo)3(μ3-(1-alkenyl)benzene) clusters 5a,b and 6a,b are prepared from CpCo(C2H4)2 (3) and α-methylstyrene, β-methylstyrene, 1,1-diphenylethylene, and stilbene. From 3 and 4-methoxystilbene a mixture of the coordination isomers of (CpCo)3(μ3-4-methoxystilbene) (7a,b) is obtained. (CpCo)3(μ3-1,1-diphenylpropene) (10) is formed from 1,1-diphenylpropene and CpCo(C6Me6) (4). Styrene and 3 do not give a μ3-styrene cluster, but (CpCo)3(μ3-4-methylstyrene) (8) and (CpCo)3(μ3-4-methoxystyrene) (9) are isolated in good yield from the reaction of 3 and the corresponding substituted styrenes. Allylbenzene, 4-methoxy(allyl)benzene, and 4-phenyl-1-butene are catalytically rearranged by 3 or 4 to the (1-alkenyl)benzene derivatives. By reaction of the further ligands with 3 molar equiv of 3 the (CpCo)3(μ3-(1-alkenyl)arene) complexes 5b, 11, and 12 are formed. The X-ray crystal structures of 5b and 6a have been determined. Crystal data: 5b, monoclinic, P21, a = 8.725 (5) A?, b = 7.542 (5) A?, c = 15.151 (6) A?, β = 103.17 (4)°, Z = 2, R = 0.026, Rw = 0.027 (w = σ-2(F)) with 2893 reflections; 6a·0.5C7H8, triclinic, P1, a = 8.734 (4) A?, b = 11.470 (5) A?, c = 12.791 (6) A?, α = 85.37 (3)°, β = 83.81 (3)°, γ = 83.52 (3)°, Z = 2, R = 0.043, Rw = 0.038 (w = σ-2(F)) with 5795 reflections. The face-capping arene rings in both compounds are coplanar with the (CpCo)3 triangles and adopt a staggered orientation. Bond length alternation within the μ3-η2:η2:η 2-coordinated arene rings is only slight, with a mean difference of 0.03 A? between longer and shorter carbon-carbon bonds. In solution rotation of the arenes on top of the (CpCo)3 triangles takes place, which can be frozen out at low temperature. The chemical reactivity of the title compounds is low. The μ3-arene ligands cannot be displaced by other arenes or by two-electron donors. Bromination, hydrosilylation, and cyclopropanation of the exocyclic alkenyl group of 5b cannot be achieved. However, catalytic hydrogenation of 5b to give (CpCo)3(μ3-n-propylbenzene) (18) proceeds readily. The relationship of the μ3-arene clusters to the metal surface adsorption states of benzene is discussed.
