Tamás Bartik

Substituenteneinflüsse auf die basizität von phosphorliganden in R3P-Ni(CO)3-komplexen

Abstract According to Tolman, the χ values of 157 P ligands can be determined exactly by FT-IR spectroscopy ( FT χ values). By replacing the phenyl groups of triphenylphosphine step-by-step by alkyl- or alkoxy-substituents, we found that Tolmans additivity rule is not strictly valid. The deviations determined from additivity give a pattern. Its shape is controlled by the DO/ACC-character of the atoms in the α-position of phosphorus. By this pattern, substituents with nearly the same FT χ i , parameters (-OCH 3 /-SPh; -t-Bu/-SiMe 3 ) but different influence on reactivity (activation/inhibition) can be recognized.

Bestimmung der Raumerfüllung von tertiären Phosphanen über 31P-NMR-spektroskopische Daten von trans-L2PdCl2-Komplexen

Abstract The 31 P NMR spectra of trans -L 2 PdCl 2 complexes (L = tertiary phosphine) were determined. Correlations between the chemical shifts δ( 31 P) and the sterical parameters of these phosphines were found. The δ( 31 P) chemical shift proved to be a useful value for characterizing the steric bulkiness of the phosphines. The chemical shifts for some new L 2 PdCl 2 complexes are given.

Darstellung und Charakterisierung von [2-(Dimethylaminomethyl)ferrocenyl]-Verbindungen des Titaniums, Zirconiums und Hafniums

Abstract [2-(Dimethylaminomethyl)ferrocenyl]lithium reacts with (η5-C5H5)2MCl2 and (η5-C5Me5)2TiCl2 to give (η5-C5H5)2M(FcN)2 and (η5-C5Me5)2Ti(FcN)Cl (M  Ti, Zr, Hf; FcN  2-(dimethylaminomethyl)ferrocenyl). The compounds were identified from their 1H and 13C NMR, IR, and mass spectra and by elemental analysis.

[2-(Dimethylaminomethyl)ferrocenyl]-Verbindungen des Zinks, Cadmiums und Quecksilbers

Abstract The (FcN) 2 M complexes (M = Zn, Cd, Hg; FcN = 2-(dimethylaminomethyl)-ferrocenyl) and FcNHgCl were synthesized from FcNLi and the corresponding metal halides. All compounds were characterized by elementary analyses. 1 H and 13 C NMR, IR and mass spectra.

Effect of water on tributylphosphine modified cobalt carbonyl catalysts for the hydroformylation of olefins

Abstract Water is seen to have a dramatic effect on the alcohol/aldehyde distribution in the P (nBu) 3 modified cobalt carbonyl catalyzed hydroformylation of 1-octene. In particular the rate of alcohol synthesis is greater in the presence of water. Under the conditions used the effect is first noticable at 5 vol.-% water. At high conversion the effect is still observed but is not as significant.

Steuerung der nickel(O)-katalysierten hydrosilylierung von phenylacetylen mit phosphorliganden

Abstract We report here the first systematic investigation of the effects of concentration and properties of tertiary phosphines on the chemoselectivity of the homogeneous catalytic hydrosilylation of phenylacetylene with triphenylsilane using Nickel(O) catalyst. The presence of P-ligands is necessary to activate the catalytic system. Between the ligand/metal ratio 1/1-2/1 hydrosilylation of phenylacetylene is preferred to trimerisation. The three-dimensional ligand profile showed that phosphines with decreasing bulkiness control the products of hydrosilylation but phosphines with increasing bulkiness yield trimers of acetylene. Hydrosilylation is enhanced when the P-ligand is either more basic or less basic than triphenylphosphine. It was found that tertiary n-alkyl and n-alkoxy-phosphines using a ligand/metal ratio 2/1 in the presence of HSiPh 3 /P h CCH = 2/1 product 85–90% hydrosilylation selectivity in preference to phenylacetylene.

Alkylcobalt carbonyls: XI. Ligand-assisted carbonylation—decarbonylation reactions of alkylcobalt carbonyls

Abstract An [(alkoxycarbonyl)methyl]cobalt tetracarbonyl ( 1 ) derivative (alkyl = Et, 1a ) was treated with tertiary phosphorus ligands. A monosubstituted acyl derivative EtOC(O)CH 2 C(O)Co(CO) 3 L ( 2 ), L = PPh 3 ( 2f ) was isolated, and other new complexes of type 2 were detected spectroscopically (L = PEt 3 , 2a ; P( i Pr) 3 , 2c ; P( t Bu) 3 , 2d ; PMePh 2 , 2e ; P(NEt 2 ) 3 , 2g ; P(OMe) 3 , 2h ; P(OEt) 3 , 2i ; P(OSiMe 3 ) 3 , 2j ; P(S i Pr) 3 , 2k ). The corresponding alkyl derivatives, EtOC(O)CH 2 Co(CO) 3 L( 3 ), were obtained by thermal decarbonylation. Disubstituted acyl-, EtOC(O)CH 2 C(O)Co(CO) 2 L 2 ( 4 ), and alkyl-, EtOC(O)CH 2 Co-(CO) 2 L 2 ( 5 ) derivatives were obtained by direct substitution at ca. 30°C and ca. 70°C, respectively. The geometries of the new complexes were deduced from spectroscopic data. The monosubstituted derivatives 2 and 3 all show a trigonal bipyramidal array with axial organyl an PR 3 ligands. All the disubstituted complexes display a trigonal bipyramidal geometry with axial organyl groups, whereas an axial-equatorial distribution of the phosphines was assigned in the case of compounds 4a , b and 5a , b , e , h , i , and an equatorial-equatorial distribution in the case of complexes 4j and 5g , j . For the alkyl complexes 5 a solvation-like interaction between the ester group and the cobalt atom (autosolvation) was indicated by spectroscopic data.

Steuerung metallkatalysierter reaktionen: XIV. kontrolle der nickel(0)-katalysierten cooligomerisation von 1,3-butadien mit vinylsilanen durch konzentration und eigenschaften von zugesetzten p-liganden☆

Abstract The effects of substituents X (X = OR, SPh, CMe 3 and SiR 3 ) in CH 2 =CHX olefins on the nickel(0)-catalyzed co-oligomerization with 1,3-butadiene were investigated. Only the vinylsilanes reacted by co-oligomerization with butadiene. The yields and product selectivities are controlled by the concentration and property (the latter characterized by Tolmans χ and θ parameters) of the added P ligands. The results are discussed in connection with the reaction mechanism. Electron-withdrawing substituents at silicon lower the reactivity of the vinylsilanes.

Organometallische Komplexverbindungen: IX. Steuerung der optischen Induktion☆

Abstract Bis(μ-methyl-1,3-dimethyl-η 3 -allyl-nickel) which has been modified with chiral P ligands reacts with carbon monoxide to give the optically active 3-methyl- E -4-hexene-2-one. Low-temperature studies (DSC, 13 C NMR) have indicated that this reaction is too fast to observe any intermediates. A suitable phosphine was chosen so that the chiral substituent is kept constant (1 R ,3 R ,4 S -(−)-menthyl) and the other two are of the same, mostly achiral type (either P(−)MenthX 2 or P(O(−)Menth)X 2 ), the extent and direction of optical induction depends strongly on the concentration and the type of P ligand examined. Furthermore, changes in achiral parts of the P ligand after special “order factors” can lead to conversion into the excess enantiomer. Up to now the usual strategy to obtain the optical antipode has been to change the chirality of the educt. Therefore both enantiomers may be necessary. In our case only one chiral precursor is needed and for this reason there is less need to draw from the natural pool, which should be useful for asymmetric synthesis.

Early/late bimetallic complexes: MCo2 (MTi, Zr) derivatives

Abstract (η5-C5H5)2M[Co(CO)4]2 (MTi, Zr) complexes were prepared by alkane elimination from the corresponding metallocene diorganyls and HCo(CO)4 or by salt elimination from metallocene dihalides and Na[Co(CO)4]. (Ph2N)2Ti[Co(CO)4]2 was obtained from (Ph2N)4Ti and HCo(CO)4.