91159-11-4Relevant academic research and scientific papers
Flexibility and Stability of Metal Coordination Macromolecules
Jiang, Heyan,Geng, Diya,Liu, Dapeng,Lanigan, Nicholas,Wang, Xiaosong
, p. 8280 - 8285 (2017)
The effect of chain structure on flexibility and stability of macromolecules containing weak P?Fe metal coordination bonds is studied. Migration insertion polymerization (MIP) of FpCXFp (1) and PR2CYPR2 (2) (Fp: CpFe(CO)2; CX and CY: alkyl spacers; P: phosphine; R: phenyl or isopropyl) generates P(1/2), in which the P?Fe and Fe?P bonds with opposite bonding direction are alternatively arranged in the backbone. On the other hand, P(FpCXP) synthesized from AB-type monomers (FpCXP) has P?Fe bonds arranged in the same direction. P(1/2) is more rigid and stable than P(FpCXP), which is attributed to the chain conformation resulting from the P?Fe bonding direction. In addition, the longer spacers render P(1/2) relatively flexible; the phenyl substituents, as compared with the isopropyl groups, improves the rigidity, thermal, and solution stability of P(1/2). It is therefore possible to incorporate weak metal coordination bonds into macromolecules with improved stability and adjustable flexibility for material processing.
Catalytic activity of cationic diphospalladium(II) complexes in the alkene/CO copolymerization in organic solvents and water in dependence on the length of the alkyl chain at the phosphine ligands
Lindner, Ekkehard,Schmid, Markus,Wald, Joachim,Queisser, Joachim A.,Gepr?gs, Michael,Wegner, Peter,Nachtigal, Christiane
, p. 173 - 187 (2007/10/03)
A series of diphos ligands CH2(CH2PR2)2 (1a-x) (a-g: R=(CH2)nOH, n=1, 3-8; h-k: R=(CH2)nCH(CH2OH)2, n=3-6; l-u: R=CnH2n+1, n=1-8, 10, 14; v-x: R=CH(CH3)2, (CH2)2CH(CH3)2, (CH2)3CH(CH3)2, (Scheme 1), provided with functionalities of different polarity, was prepared photochemically by hydrophosphination of the corresponding 1-alkenes with H2P(CH2)3PH2 or reaction of Grignard reagents with Cl2P(CH2)3PCl2. The water-soluble palladium complexes [(R2P(CH2)3PR2)Pd(OAc)2] (2a-k) were obtained by reaction of Pd(OAc)2 with the ligands 1a-k in ethanol-acetonitrile. Treatment of PdCl2(NCC6H5)2 with 1l-x afforded the dichloropalladium(II) complexes [(R2P(CH2)3PR2)PdCl2] (3l-x). Upon chloride abstraction with AgBF4 in dichloromethane-acetonitrile the dicationic palladium(II) complexes [(R2P(CH2)3PR2)Pd(NCCH 3)2][BF4]2 (4l-x) are formed. The structure of 4n (R=n-Pr) was investigated by an X-ray structural analysis. In particular the water-soluble complexes 2c-k proved to be highly active in the carbon monoxide/ethene copolymerization under biphasic conditions (water-toluene). In the presence of an emulsifier and methanol as activator the catalytic activity increased by a factor of about three. Also higher olefins could be successfully incorporated into the copolymerization with CO and the terpolymerization with ethene and CO. The catalytic activity of the dicationic complexes 4l-x in the propene or 1-hexene/CO copolymerization strongly depends on the length of the alkyl chain R. At 25°C a maximum is achieved in the case of 4q (R=nHex) which is five times more active than the corresponding catalyst with the dppp-ligand. This maximum is shifted to 4t (R=n-C10H21) if the temperature is raised to 60°C. The 1-alkene/CO copolymers are distinguished by their regioregular microstructure and their ultra high molecular weights. Compared to the sulfonated dppp-SO3 catalyst the water-soluble complexes 2c,e,f,h are responsible for a higher 1-hexene incorporation in the terpolymerization of ethene with 1-hexene and CO.
Co-dimerization of vinyl aromatics with α-monoolefins
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, (2008/06/13)
The invention concerns a process for the co-dimerization of a vinyl aromatic monomer (e.g. styrene) with an α-monoolefin monomer (e.g. ethylene, propylene or 1-butylene), using a catalyst composition comprising palladium, an anion of a strong acid and an aliphatic diphosphine.
MECHANISTIC ASPECTS OF CATALYTIC HYDROGENATION OF KETONES BY RHODIUM(I)-PERALKYLDIPHOSPHINE COMPLEXES
Tani, Kazuhide,Tanigawa, Eiji,Tatsuno, Yoshitaka,Otsuka, Sei
, p. 87 - 102 (2007/10/02)
Mechanistic aspects of the hydrogenation of ketones employing cationic rhodium(I) complexes ClO4 (NBD=norbornadiene) and ClO4 (CyDIOP=2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(dicyclohexylphosphino)butane) and a neutral complex, "Rh(CyDIOP)Cl" were studied.The cationic complex-catalyzed hydrogenation of the poor coordinating simple ketone substrates followed a rate equation r0=kobs00 and showed an unusual negative temperature dependence of the reaction rate.The hydrogenation of the chelating substrate PhCOCONHCH2Ph followed a rate equation r0=kobs with the activation parameters Ea 5.51 kcal mol-1, ΔH excit.308 4.90 kcal mol-1, ΔS excit.308-32.0 e.u. (ClO4 catalyst); Ea 5.36 kcal mol-1, ΔH excit.308 4.75 kcal mol-1, ΔS excit.308-30.9 e.u. (ClO4 catalyst).For the neutral complex-catalyzed hydrogenation of PhCOCONHCH2Ph, the rate equation r0=0.2500 was obtained with the activation parameters (Ea 3.99 kcal mol-1, ΔH excit308 3.38 kcal mol-1, ΔS excit.308-43.0 e.u.) Several intermediate complexes in the cationic complex-catalyzed hydrogenation were alo detected spectroscopically or isolated.On the basis of these observations, a general scheme was proposed.
