23732-79-8Relevant academic research and scientific papers
Chemistry of Metallacyclobutanones. Part 2. Synthesis and Ring Inversion of some Highly Puckered Metallacyclobutan-3-one (Slipped Oxodimethylenemethane) Complexes of Palladium; Crystal Structures of 2,4-Bis(methoxycarbonyl)-1,1-bis(triphenylphosphine)palladacyclobutan-3-one, 2,4-Bis(m...
Kemmitt, Raymond D. W.,McKenna, Peter,Russel, David R.,Sherry, Lesley J. S.
, p. 259 - 268 (1985)
The reactions of the zerovalent palladium complex *CHCl3 (dba=dibenzylideneacetone, PhCH=CH-C(O)-CH=CHPh), in the presence of a donor ligand L and dioxygen, with esters of 3-oxopentanedioic acid (RCH2COCH2R) in diethyl ether, afford, in high yield, the palladacyclobutan-3-one compounds n, L2=bipy>.The compounds (R=CO2Me or CO2Et, L=PPh3 or AsPh3) are also formed upon treatment of benzene solutions of with RCH2COCH2R in the presence of air.Treatment of the ketone MeO2CCH2COCH2CO2Me with either in benzene or in ethanol also affords .Spectroscopic data (i.r. and n.m.r.) for the new compounds are reported, and discussed in relation to their structures, which were firmly established for by single-crystal X-ray diffraction studies.Crystals of (3a) are triclinic, space group P1/, Z=2, in a unit cell with lattice parameters a=11.995(5), b=17.72(1), c=10.30(1) Angstroem, α=94.7(1), β=110.8(1), and γ=102.84(2) deg.The structure was refined to R 0.055 (R' 0.060) for 5093 reflections having 7αX-radiation) collected at room temperature.Crystals of (3e) are triclinic, space group P1/, Z=2, in a unit cell with lattice parameters a=12.219(6), b=17.56(1), c=10.44(1) Angstroem, α=93.3(1), β=110.8(1), and γ=103.56(2) deg.The structure was refined to R 0.043 (R' 0.046) for 6025 reflections having 71/c, Z=4, in a unit cell with lattice parameters a=8.43(1), b=14.594(6), c=14.170(6) Angstroem, and β=92.1(1) deg.The structure was refined to R 0.043 (R' 0.032) for 4000 reflections having 7a highly puckered palladacyclobutan-3-one ring with a weak transannular Pd-C bond .The molecules can be alternatively formulated with slipped η3-oxodimethylenemethane ligands.Variable-temperature 1H n.m.r. data for the compounds (R=CO2Me, L=PPh3, PMePh2, PMe2Ph, PEt3, or AsPh3; L2=bipy) are interpreted in terms of inversion of the palladacyclobutan-3-one ring through a planar transition state.
Synthesis and optical properties of a poly(2′,5′-dioctyloxy-4,4′,4″- terphenylenevinylene) with high content of (Z) vinylene units
Babudri, Francesco,Cardone, Antonio,Cassano, Tiziana,Farinola, Gianluca M.,Naso, Francesco,Tommasi, Raffaele
, p. 2631 - 2636 (2008/09/21)
Poly(2′,5′-dioctyloxy-4,4′,4″-terphenylenevinylene) with (E) configuration of the vinylene double bonds was prepared by Suzuki-Miyaura polymerization of (E)-4,4′-dibromostilbene and 2,5-dioctyloxy-1,4-benzenediboronic acid. Attempts to extend this simple procedure to the synthesis of the polymer with (Z) configuration, starting from (Z)-4,4′-dibromostilbene, were unsuccessful. However, the use of (Z)-4,4′-diiodostilbene and a careful choice of Pd catalyst and experimental conditions, lead to a material with a >95/5 (Z)/(E) ratio of vinylene units. The investigation of optical properties of both the (E) and (Z) polymers evidenced that (Z) linkages act as defects which reduce the effective conjugation length in the polymer backbone.
