Richard Korswagen
Pontifical Catholic University of Peru
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Journal of Organometallic Chemistry | 1988
K. Endrich; Ernst Guggolz; O. Serhadle; Manfred L. Ziegler; Richard Korswagen
Abstract Condensation of chalcogenide vapours (S, Se, Te) onto a THF matrix containing the species (C 5 R 5 ) 2 M 2 (CO) 4 (MM) (R = H, CH 3 ; M = Cr, Mo, W) in a metal vapour apparatus (temperature of liquid nitrogen, 10 −4 bar) upon warming (S 10, Se 15, Te 5 (CH 3 ) 5 W 2 (CO) 4 E 3 (E = S ( 2 ), Se ( 13 )) and (C 5 (CH 3 ) 5 ) 2 W 2 (CO) 4 E 2 (Se, ( 13a ), Te ( 17 )). The species, which are primary adducts of the chalcogenides to the WW bond, could not be synthesized by the “thermic” reactions reported in the literature. The species 2 and 13 are readily converted into the chalcogenide complexes such as (C 5 (CH 3 ) 5 ) 2 Mo 2 O 2 Se ( 16 ) liberating CO. 17 was protonated to give the complex salt [(C 5 (CH 3 ) 5 ) 2 W 2 (CO) 4 (Te 2 H 2 )] 2+ [BF 4 ] 2 − ( 18 ) by HBF 4 . The compounds were characterized by elemental analysis and their spectroscopic data, X-ray diffraction studies of 13a, 16 and 18 are described.
Journal of Organometallic Chemistry | 1986
María Inés Altbach; César A. Muedas; Richard Korswagen; Manfred L. Ziegler
Abstract The cis / trans isomerization of the bridging methylene complex {(μ-CH2)(μ-CO)[η5-C5H5-Fe(CO)]2} was studied in solution by 1H NMR spectrometry, using solvents with different polarities (acetone-d6, chloroform-d1 and benzene-d6). Equilibrium constants and rate constants for the forward and reverse steps were measured between 278 and 323 k. Both reactions show first-order kinetics. A possible mechanism for the isomerization is proposed, involving the breaking of a FeFe bond in the rate-determining step.
Journal of Organometallic Chemistry | 1989
Celia Caballero; Jorge Chávez; Ömer Göknur; Inge Löchel; Bernhard Nuber; Heike Pfisterer; Manfred L. Ziegler; Pía Alburquerque; Liliana Eguren; Richard Korswagen
Abstract Reaction of [Cp′Fe(CO) 2 ] 2 ( 1b (Cp′ = MeC 5 H 4 ) with the phosphorus ylide Ph 3 PCH 2 yields two products. {μ-CH 2 )(μ-CO)[Cp′Fe(CO)] 2 } ( 2b ) and Cp′(CO)(PPh 3 )Fe(COCH 3 ) ( 4 ). The crystal structure analysis of 2b is reported. It is shown, that with different phosphorus ylides the reaction of [CpFe(CO) 2 ] 2 ( 1a ) (CP = C 5 H 5 ) proceeds differently depending also on the amount of n-butyllithium present. So a threefold excess of the LiX adducts (X = Cl, Br) of the ylides Ph 3 PCHR in the presence of a large excess of n-butyllithium gives metallacyclic compounds of composition Cp(CO)Fe{HRCP(C 6 H 4 )Ph 2 } (R = H ( 3a ), R = CH 3 ( 3b ), R = C 2 H 5 ( 3c )) in the case of alkylidene ylides and Cp(CO)(PPh 3 )FeCH 2 Ph ( 5 ) with the benzylidene ylide (R = C 6 H 5 ). In the presence of a large excess of n-butyllithium, a twofold excess of Ph 3 PCHPh reacts with 1a to give the compound C 32 H 23 FeO 2 P ( 6 ) characterized by spectroscopic data and an X-ray diffraction study. In 6 an η 3 -cyclopentyl ring is coordinated to the iron atom together with two CO ligands, a phenyl ring and an ylidic carbon atom. Also characterized by an X-ray diffraction study was 3c , which was found to have a metallacycle containing an iron and a phosphorous atom, the ylidic carbon and two carbon atoms from one “phenyl” ring of the PPh 3 group as ring members. Reaction of (CH 3 ) 2 PhPCH 2 ·LiI with 1a gives extremely air-sensitive monophosphonioalkyl complex {(ηCo) 2 [CpFe(CO)][CpFeL]} ( 8 ) (L = Me 3 PCH 2 ). Some mechanistic considerations on the various reaction types of 1a based on the data obtained are presented.
Zeitschrift für Naturforschung B | 1988
K Endrich; P Alburquerque; Richard Korswagen; Manfred L. Ziegler
We report first the complete study of the reactions of [CpMo(CO)2]2 (Mo≡Mo) (1, Cp = η5-C5H5) with salt-free phosphorus ylides Ph3P=CHR (2, Ph = C6H5; R = H (2a), CH3 (2b), C3H7 (2c), C6H5 (2d)) and with the Nal-adducts of the ylides Ph3P=CMe2 (Me = CH3), PhMe2P=CH2 and (PhO)3P=CH2. With 2, products of the type Cp(CO)2LMo-MoL(CO)2Cp (7, L = ylide) were obtained, and the salt adducts gave addition compounds of the type Cp(CO)2LMo-MoL(CO)2Cp-2NaI (12, L = ylide). These very reactive products represent novel bisphosphonioalkyl complexes, and were characterized by IR, mass and 1H NMR spectrometry. The reaction of 1 with hexaphenylcarbodiphosphorane, C(PPh3)2, leads to a novel double addition product, Cp2Mo2(CO)4[C(PPh3)2]2 (14). Some reactions of compounds 7, 12 and 14 were also studied; 7d (L = CHPh -PPh3) reacts with NaNH2 yielding ammonia and the disodium salt of the novel dianionic complex [CpMo(CO)2(CPh-PPh3)]22- (15); 7a (L = CH2-PPh3) reacts with CH3I forming CpMo(CO)3CH3 and traces of CpMo(CO)2(PPh3)I; all compounds of types 7,12 and 14 react with adsorbents (Silica-gel, Al2O3, etc.); thus chromatography is impossible, even under strict protection from air and humidity. A study of the processes occurring during chromatography under various conditions and the resulting products are also reported and discussed. [CpW(CO)3]2 (18) reacts with 2a forming also a bisphosphonioalkyl complex [CpW(CO)2L]2(L = CH2=PPh3); in this case, the ylide substitutes two carbonyl groups in 18. The compounds [Cp*M(CO)2]2 (M≡M) (Cp* = C5Me5 ; M = Cr, W) apparently do not react with phosphorous ylides; the corresponding Mo compound, [Cp*Mo(CO)2]2 , does react, but only the new mono-nuclear complex Cp*Mo(CO)2(PPh3)Cl (22) could be isolated.
Zeitschrift für Naturforschung B | 1988
Manfred L. Ziegler; Klaus Blechschmitt; Harald Bock; Ernst Guggolz; Richard Korswagen
Abstract In this paper we report two improved preparation methods for [(CH3)2N]6W2 (W≡W) (1), one starting from WCl4 (yield 51%), and a second one starting from W2C16(THF)4 (ca. 60% yield). We have studied the reactions of 1 with different nucleophiles, among them triphenylalkylidenphosphoranes (like Ph3P=CH2 and Ph3P=CHPh·LiCl; Ph = phenyl), sulfur and CS2 . 1 reacts with S8 and CS2 in hexane to yield the two new compounds (Me2NCS2)2WS(S2) (4) and W(CS2H)(Me2NCS2)2 (5), both containing dithiocarbamato ligands formed by insertion of CS2 into the W-N bond. The two mononuclear compounds were characterized spectroscopically, in the case of 4 an X-ray diffraction structure analysis was performed. The reaction of 1 with Se and CS2 , leads to the compounds 4, (Me2NCS2)2W2S4 (6) and [(Me2N)2C]CS2 (7), which were also characterized spectroscopically. No Se-containing compounds could be isolated. 4 crystallizes monoclinically, C52h-P21/n, with a = 648.6(3), b = 1346.7(6) and c = 1745.9(7) pm, β = 91.85(3)°, V = 1524x106 pm3 , Z = 4. The structure of the seven-coordinate tungsten compound is discussed and compared to complexes with similar ligands and geometry.
Zeitschrift für Naturforschung B | 1979
Richard Korswagen; Klaus Weidenhammer; Manfred L. Ziegler
The photolytical reactions of η5-C5H5Mo(CO)3CH3 (1) or η5-C5H5W(CO)3CH3 (2) with N3CO2C2H3 (3) in CH2Cl2 yield the “nitrene” complexes [(η5-C5H5JMoO)(μ-NCO2C2H5)2 (4), [(η5-C5H5)WO]2(μ-NCO2C2H5)2 (5) and [(η-C5H5JMoO]2(μ-NCO2H5)(μ-O) (6) together with some η5-C5H5Mo(CO)3Cl (7) and η5-C5H5W(CO)3Cl (8), proving that the solvent takes part in the reaction. Compounds 4, 5 and 6 contain bridging imido groups, arising from the capture of probably free nitrenes NCO2C2H5 by organometallic species. Evidence for the presence of free nitrenes in the reaction medium is provided by the isolation of urethane (9), tetrachlorethene (10), 7 and 8 as secondary products.
Angewandte Chemie | 1981
Richard Korswagen; Reinhold Alt; Dieter Speth; Manfred L. Ziegler
Angewandte Chemie | 1982
Klaus Endrich; Richard Korswagen; Thomas Zahn; Manfred L. Ziegler
Angewandte Chemie | 1981
Richard Korswagen; Reinhold Alt; Dieter Speth; Manfred L. Ziegler
Angewandte Chemie | 1982
Klaus Endrich; Richard Korswagen; Thomas Zahn; Manfred L. Ziegler