摘要:

AbstractIn the late 1940s,Reppediscovered a nickel catalyst for the co‐oligomerization of ethene and carbon monoxide. Since then, various groups have made attempts to develop more efficient catalysts for this reaction. The recent discovery of a new class of very active palladium catalysts now allows, for the first time, ready access to a large variety of high‐molecular‐weight alkene/carbon‐monoxide co‐ and terpolymers. The catalysts comprise acis‐coordinated palladium(II) species associated with weakly or non‐coordinating anions. Their discovery has made it possible to develop a viable process for the commercial production of the first members of the new family of CARILON‐olefin/carbon monoxide copolymers.In this brief review, we highlight some key phenomena in polyketone catalysis. The elementary reaction steps in the palladium‐catalyzed polyketone formation during chain propagation, initiation and termination are outlined. The role of bidentate ligands and the reasons for perfect alternation in polymer chain growth are dicussed. The attractive feature of the catalysts, that they also catalyze the co‐ and terpolymerization of olefins higher than ethene with carbon monoxide, is briefly noted. A parallel between polyketone catalysis by cationic palladium complexes and modern polyolefin catalysis by cationic metallocene com

ISSN:0165-0513    

DOI:10.1002/recl.19961150502

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractHydrogenolyses of hexadeuterobenzene C6D6and pentadeuterochlorobenzene C6D5Cl have been studied in flow reactors packed with activated carbon (AC) between 300° and 600°C, with void residence times of 4‐5 s. At 579°C overall dedeuteration ‐ proceeding in a near statistical manner ‐ was close to 40% in both cases, whereas C6D5Cl is almost completely dechlorinated to deuterated benzenes at 505°C. On a per‐site basis, replacement of Cl by H isca.20 times faster than that of D.These results clearly demonstrate a catalytic activity ofACin both cases of desubstitution. In the absence ofAC, temperatures of 700‐900°C are necessary to obtain the same result. Then, replacement of Cl and D have almost equal rates, both reactions occurringviaaddition of free H atoms. In theAC‐mediated reactions, the yields of (D) benzenes are quantitative from C6D6, but around 50% with C6D5Cl. Apparently the latter compound reacts with bonding of its phenyl group to theACsurface, whereas D → H substitutions involve H transfer to a physi

ISSN:0165-0513    

DOI:10.1002/recl.19961150503

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe synthesis and characterization of substituted phenanthrene‐9,10‐quinone diimines of the type 9,10‐bis(arylimino)‐9,10‐dihydrophenanthrene (aryl‐BIP) is described. These rigid bisnitrogen ligands have been synthesized by a metal‐mediated cyclodehydrogenation reaction from the aromatic open‐chain diimine analogues derived from benzil. All aryl‐BIP compounds adopt aZ,Zconfiguration in solution except for (o‐iPr‐phenyl)‐BIP, which mainly exists in theE,Zform. All non‐cyclic BIP compounds undergo a configurational change into theE,Eisomer upon coordination to palladium. NDDO calculations on phenyl‐BIP and its palladium dichloride complex have revealed that the energy of the LUMO is very much dependent on the puckering of the phenanthrene backbone and is in all cases lower than, for instance, that of the aromatic diimine of acenaphthene‐1,2‐quinone or open‐chain diimines. The structures of phenyl‐BIP and PdCl2‐(phenyl‐BIP) in the solid state have been determined by X‐ray diffraction. Phenyl‐BIP is triclinic, space groupP̄, a= 12.392(1),b= 12.478(1),c= 14.633(2) Å, α = 109.36(1), β = 91.57(1), γ = 115.82(1)°,Z= 4, finalR= 0.0556 for 4494 reflections withI>2.5σ(I). PdCl2‐(phenyl‐BIP) is monoclinic, space groupP21/c, a= 20.5148(9),b= 10.6756(9),c= 23.2007(16) Å, β = 105.13(1)

ISSN:0165-0513    

DOI:10.1002/recl.19961150504

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe reaction of [PdCl2(MeCN)2] with one or two equivalents of Me3SiSC6H4NMe2‐2 in toluene affords the mono(arenethiolate) complex [PdCl(SC6H4NMe2‐2)] (1) or the bis(arenethiolate) complex [Pd(SC6H4NMe2‐2)2] (2), respectively, in high yields. [PdCl(SC6H4NMe2‐2)] (1) exists as a tetramer in the solid state (X‐ray) while [Pd(SC6H4NMe2‐2)2] (2) is a monomer both in the solid state and in solution (cryoscopy, NMR). The X‐ray structure determination of tetrameric1shows arenethiolate ligands bridging between PdCl units to form a unique eight‐membered U‐shaped Pd4S4ring. Crystals of1are tetragonal, space group, witha = b= 12.0495(10) Å,c= 16.672(1) Å,V= 2420.6(3) Å3,Z= 2, and finalR= 0.029,wR= 0.034 andS= 1.42 for 1174 reflections withI>2.5 σ(I) and 111 variables. The X‐ray structure determination of2shows it to be monomeric in the solid state. The palladium has a square‐planar geometry that results from coordination by twoS,N‐chelating arenethiolate ligands with atransS andtransN arrangement of the donor atoms. Crystals of2are triclinic, space group, witha= 8.9923(5) Å,b= 9.2472(5) Å,c= 11.5933(6) Å,V= 825.93(9) Å3,Z= 2, and finalR= 0.025,wR= 0.047 andS= 0.53 for 3603 reflections w

ISSN:0165-0513    

DOI:10.1002/recl.19961150505

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe sulfodeprotonation oftrans‐10b,10c‐dimethyl‐10b,10c‐dihydropyrene (1) with sulfur trioxide has been studied in dioxane as solvent, as well as in dichloromethane, using 4.0–5.0 equivalents of dioxane relative to the amount of SO3as reactivity moderator. Reaction of1with 0.6 mol‐equiv. of SO3in dioxane at 22°C yields initially only the 2‐ and 4‐sulfonic acid in a 84/16 ratio. Using 3.0‐6.0 mol‐equiv. of SO3in dichloromethane with the temperature increasing from −78 up to 22°C the initially very rapid formation of the 1‐, 2‐ and 4‐sulfonic acid (formed in a ratio of 11/82/7) is followed by a much slower conversion into a mixture of 1,7‐, 2,4‐, 2,5‐ and 2,7‐disulfonic acid. These four acids are subsequently converted even more slowly into a mixture of the 1,4,7‐, 2,4,7‐ and 2,5,9‐trisulfonic acids to yield in part the 1,4,7,9‐, 2,4,7,9‐ and 2,4,7,10‐tetrasulfonic acids.trans‐2,7‐Di‐tert‐butyl‐10b, 10c‐dimethyl‐10b, 10c‐dihydropyrene (2) with 0.8–2.0 equiv. of SO3in dioxane as solvent gives the 4‐sulfonic acid which is slowly converted into a 16/84 mixture of the 4,9‐ and 4,10‐disulfonic acids.The observed distributions of sulfonic acid isomers are discussed in terms of the directing effects of the “ideal” ‐ almost plana

ISSN:0165-0513    

DOI:10.1002/recl.19961150506

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19961150507

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractTwo rigidly bridged electron donor‐acceptor systems are reported that display discrete, intramolecular charge‐transfer (CT) absorption and emission spectra in solution at room temperature. For both the CT‐absorption is highly structured irrespective of solvent, for one also the CT‐fluorescence in a nonpolar solvent is str

ISSN:0165-0513    

DOI:10.1002/recl.19961150508

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19961150510

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19961150512

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19961150501

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY