摘要:

AbstractTransition metal organometallic homogeneous catalysts depend on the ease of ligand substitution in one or more of the catalytic steps. Thus, it follows that the more we learn about the factors which affect rates of ligand substitution, the better we will be able to design useful catalysts. Three different types of approaches to the enhancement of ligand substitution are discussed. These are (1) through the use of spectator ligands which permit an 18‐electron system to react by an associative process, (2) the relative rates of substitution of a 17‐electron and a corresponding 18‐electron system, and (3) the reactivity order 1st row3rd row transition metals for a given metal triad. Specific examples are given for each of these approaches to generate more substitution labile organometallic comp

ISSN:0021-2148    

DOI:10.1002/ijch.198600035

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0021-2148    

DOI:10.1002/ijch.198600036

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractA number of catalysts of Pd(II), Pt (II), Rh (I) and Ir(I) induce rearrangements of O‐allylic‐S‐methyl dithiocarbonates at 25° C. For most substrates, the Pd(II) and Pt(II) catalysts cause [3,3] sigmatropic (Claisen) rearrangements but the Rh(I) and Ir(I) catalysts give, in addition, other products depending on the catalyst and the substrate. The Claisen rearrangements observed with the Pd(II) and Pt(II) catalysts are believed to occur by a cyclization induced mechanism, whereas those rearrangements associated with the Rh(I) and Ir(I) catalysts, as well as in one case with the Pd(II) catalyst, appear to involve metal stabilized carbocation intermediates. When cyclic substrates are used retention of configuration is observed predominantly for all catalysts

ISSN:0021-2148    

DOI:10.1002/ijch.198600037

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractN‐Alkylformamides, polymeric polyamines, and tertiary aliphatic and araliphatic amines, have been prepared using ruthenium homogeneous catalysis and synthesis gas as a basic building block. N,N‐dimethylformamide, for example, has been generated by a new synthesis route, directly from syngas plus ammonia, using the concept of ruthenium “melt” catalysis. Polymeric polyamine derivatives of 1,2‐polybutadienes have been prepared via the aminomethylation reaction using a two‐phase medium to facilitate product‐cataly

ISSN:0021-2148    

DOI:10.1002/ijch.198600038

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe carbon monoxide uptake in the reaction of allylbenzene with CoH(CO)4in n‐octane leading to acylcobalt tetracarbonyls and aldehydes is catalyzed by Co2(CO)8. The rate is half order in Co2(CO)8, first order in allylbenzene and shows a complex dependence in CoH(CO)4and CO. From kinetic experiments between 15 and 45° C the temperature dependence of the observed rate constant was determined. The complete analogy of this kinetics with that obtained for heptene‐1 shows that the main aldehydic product 2‐phenylbutyraldehyde is formed by a mechanism characteristic for aliphatic olefins and not by one operative for st

ISSN:0021-2148    

DOI:10.1002/ijch.198600039

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractAn evaluation of the catalytic reactivity of [CPD (CO)2RuH]2(1) and (CPD)(CO)3Ru (2) (where CPD = tetraphenylcyclopentadienone) with amines suggests that these complexes catalyze C‐N bond cleavage by activating C‐H bonds alpha to the nitrogen atom of tertiary, secondary and primary amines at ca. 140° C. When two different amines are used, transalkylation takes place. With secondary and primary amines, ammonia and tertiary amines are formed. A series of amine complexes (CPD)(CO)2Ru.NR3(R = alkyl/H) was isolated from stoichiometric reactions of 1 or 2 with primary and secondary amines. It was found that tertiary amines do not generate complexes of the above type but rather unexpectedly give secondary amine complexes by cleavage of an alkyl group. The only isolatable tertiary amine complex is the moderately stable (CPD)(CO)2RuNMe3. All amine complexes were characterized by spectral and elemental analyses. Catalytic aspects of C‐N bond cleavage were studied. Complexes (1) and (2) were found to react with primary, secondary and tertiary amines to generate imminium or eneamine species which subsequently undergo hydrolysis with water. This is in contrast to the Ru carbene mechanism previously proposed for cluster catalyzed C‐N bond activation and cleavage. The two reactions are compared with respect to D for H exchange (with D2O), water requirement and production of trace products during catalysis. A primary alcohol was found to substitute alkyl groups of a tertiary amine under the catalytic action of 1. A catalytic reaction cycle is

ISSN:0021-2148    

DOI:10.1002/ijch.198600040

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe novel complex (4‐cyclooctene‐l‐yl)‐ bis(trifluoroacetamido) nickel oligomerizes ethene to olefins of about 85% linearity. Unusual high activities of 11500 mol ethene/mol nickel were obtained. Also higher α‐olefins such as propene, butene or octene could be oligomerized yielding 70‐80% linear dimers. By using (4‐cyclooctene‐1‐yl)(1,1,1,5,5,5‐hexafluoro‐2,4‐pentanedionato) nickel activated by BF3the bulky olefin neohexene was converted selectively into dimers, which are linear, con

ISSN:0021-2148    

DOI:10.1002/ijch.198600041

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe tervalent nickel complex with C‐meso‐ 5,7,7,12,14,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane, Ni‐(III)L, as its disulphate form, Ni(III)L(SO4)2, oxidizes cresols in aqueous solutions. The major products after two electron equivalents are consumed are the corresponding hydroxybenzyl alcohols. The products after four electron equivalents are consumed are the corresponding hydroxybenzaldehydes. Excess tervalent nickel does not lead to the formation of the corresponding hydroxybenzoic acids. The results indicate that the oxidation reactions observed occur via the outer sphere mechanism. The use of NiL2+as a catalyst for the oxidation of cresols i

ISSN:0021-2148    

DOI:10.1002/ijch.198600042

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0021-2148    

DOI:10.1002/ijch.198600034

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY