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  • 1
    ISSN: 0009-2940
    Keywords: Ruthenium compounds ; Osmium compounds ; Alkynes, activated ; Cyclotrimerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Depending on the substituents, the reaction of the activated alkynes ZC≡CZ (2a-g) [Z = CO2R: R = Me (a), Et (b); Z = R1: R1 = CF3 (c), CH2Cl (d), CH2Br (e); Z = CH2OC(O)R2: R2 = Me (f), CCl3 (g)] with the labile ruthenium complex (η2-C2H4)Ru(CO)4 (1) results in the formation of three different types of heterocycles. While the reactions of the dialkyl acet-ylenedicarboxylates 2a, b lead to the dimeric tricarbonylru-thenacyclopentadienes 3a, b, being catalytically active in the cyclotrimerization of alkynes like 2a, b, the application of the 1,4-halogeno-2-butynes 2c-e yields the bicyclic heterocycles 4c-e. The esters of 2-butyne-1,4-diol 2f, g are converted into the tetracarbonylruthenacyclopentadienes 5f, g. Investigation of the primary attack of the alkynes 2a-g at complex 1 leads to the conclusion, that an ionic mechanism is preferred in the ruthenium-catalyzed cyclotrimerization of electron-poor alkynes. If, instead of 1, (η2-C2H4)Os(CO)4 (6) is allowed to react with the acetylenes 2a, b the osmium complexes (η4-C6Z6)Os(CO)3 (7a, b) are isolated. In the presence of CO at 2 bar 7a, b release the benzene derivatives C6Z6 (8a, b) with the formation of Os3(CO)12.
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  • 2
    ISSN: 0009-2940
    Keywords: Ruthenium(II) complexes ; Ether phosphanes ; Fluxional behavior ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, Crystal Structure, and Fluxional Behavior of cis-Cl2Ru(CO)(P∽O)(P^O) with cis-Positioned (Ether-Phosphane) LigandsReaction of the ether-phosphane ligands 2a-c with Cl2Ru-(PPh3)3 (1) results in the formation of the bis(chelate) complexes trans-Cl2Ru(P^O)2 (3a-c) (P∽O = η1-P-coordinated; Pb̂O = η2-O,P-coordinated). With CO both Ru-O bonds are cleaved to give all-trans-Cl2Ru(CO)2(P∽O)2 (4a-c). The mono(chelate) complexes 5a-c are obtained from stoichiometric amounts of 3a-c and 4a-c. Upon heating the kinetically controlled products 5a-c are transformed into the thermodynamically more stable isomers cis-Cl2Ru(CO)(P∽O)(P^O) (6a-c). Both 5a-c and 6a-c show fluxional behavior. The higher coalescence temperatures and estimated ΔG≠ values of 6a-c (75, 67, and 70°C, respectively) compared to 5a-c (55, 0, and -10°C, respectively) indicate different exchange mechanisms for 5 and 6. According to an X-ray structure analysis, 6b crystallizes in the monoclinic space group P21/c with Z = 4. The action of CO on 6a-c affords the cis,cis,trans complexes 7a-c.
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  • 3
    ISSN: 0009-2940
    Keywords: Palladium complexes ; Ether-phosphanes ; NMR, 31P, dynamic, line-shape analysis ; Fluxional behavior ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fluxional Behavior of Cationic cis Bis(ether-phosphane)palladium(II) Complexes. - 31P-DNMR Spectroscopic Investigations, Line-Shape Analysis, and Determination of Rearrangement BarriersHerrn Professor Heinrich Nöth zum 65. Geburtstag gewidmet.Reaction of X2Pd(P∼O)2 (X=Cl: 1a - g, k - n, p; X=Br: 1′; X=I: k″, l″, o″) with stoichiometric amounts of AgClO4 results in the formation of the monochelate complexes cis-[ClPd(P∼O)(P∩O)][ClO4] (2a - g, k - n, p, l′, l″) (P∼O: η11-P-coordinated; P∩O: η21-O,P-chelated). In the case of compounds 1o, 1k″, and 1o″, which are provided with less basic etherphosphanes, the halide-bridged dimers [(μ1-X)Pd(P∼O)2]2[ClO4]2 (3o, k″, o″) are obtained. Temperature-dependent 31P{1H}1-NMR spectra of the fluxional complexes 2a - g, k - n, p, l′, l″ lead to δG≢ values. By using a modified version of DNMR5, computer-generated spectra of 2a, b, f, k, l, p, l′, l″ were obtained and fitted to the experimental spectra. Graphic application of the Eyring equation to the kinetic data afforded the thermodynamic parameters δH≢, δS≢, and δG≢. The δS≢ values are in agreement with an associative exchange mechanism for 2a, b, f, l, p, l′, l″ and with a dissociative exchange mechanism for 2k, 2k and 3o crystallize in the monoclinic and triclinic space group P21/c and P&1marc; with Z=4 and Z=2, respectively.
    Additional Material: 2 Ill.
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  • 4
    ISSN: 0009-2940
    Keywords: Cyclocotrimerization ; Selenophosphinites ; Alkynes, activated ; Selenophenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selenophosphinito complexes (OC)4Mn(η2-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PR21) (2a, b) [R1 = cyc-Hex (a), tBu (b)] are formed by the reaction of BrMn(CO)5 with the phosphane selenides R21HPSe (1a, b) in the presence of the auxiliary base Et(iPr)2N. According to an X-ray structural analysis, 2a crystallizes in the space group \documentclass{article}\pagestyle{empty}\begin{document}$ P\bar 1 $\end{document} with Z = 2. The dimeric complex [(OC)4Mn(μ-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PMe2)]2 (4c) is not obtained in a straightforward way. Compound 4c is only obtained via the intermediate Br(OC)4Mn-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}P(H)Me2 (3c) by HBr elimination with nBuLi. Complex 3c is formed by replacement of carbon monoxide in BrMn(CO)5 by Me2HPSe (1c). A dissociative equilibrium between [(OC)4 Mn(μ-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PMe2)]2 (4c) and the monomeric species (OC)4Mn(\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}2-Se\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}PMe2) was not observed. The cyclocotrimerization of the 〉P\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ \dddot - $\end{document}Se function with the activated alkynes ZC≡CZ [Z = CO2R2; R2 = Me (d), Et (e), iPr (f), cyc-Hex (g)] was successful only in the case of the cyclohexyl derivative 2a to give the selenaphosphamanganabicycloheptadienes 5d - g. An X-ray structural analysis proved that 5d crystallizes in the space group \documentclass{article}\pagestyle{empty}\begin{document}$ P\bar 1 $\end{document} with Z = 2. Under CO pressure 5d was degraded to the selenophene 6.
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