Abstracts

Carben-, Vinyliden- und Allenyliden-Komplexe des Rutheniums mit Heteroskorpionat-Liganden

Henning Kopf Dissertation der Universität Konstanz 2008.
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Erschienen im Cuvillier-Verlag (ISBN-13: 9783867277921)
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Im Rahmen der vorliegenden Dissertation wurden neutrale Carben-, Vinyliden- und Allenyliden-Komplexe mit Bispyrazolylacetato-Liganden synthetisiert und charakterisiert. Die erhaltenen Komplexe wiesen fast durchgängig eine für Organometallverbindungen sehr hohe Stabilität gegenüber Sauerstoff und Wasser auf. Für die Benzyliden-Komplexe wurde Aktivität als Katalysatoren in der Ringschlussmetathese gefunden. Fragen zur strukturellen Isomerie wurden mittels zweidimensionaler NMR-Experimente und Röntgenstrukturanalysen untersucht. Mechanistische Untersuchungen wurden durch DFT-Rechnungen unterstützt.

Within this dissertation neutral carbene-, vinylidene- and allenylidene-complexes with bispyrazolylacetato-ligands have been synthesized and characterized. Nearly all complexed showed very high stability toward oxygen and water. For the benzylidene-complexes activity as catalysts in ring closing metathesis reaction was found. Issues concerning structural isomerism were investigated using two-dimensional NMR-experiments and X-ray structure analyses. Mechanistic explorations were supported by DFT-calculations.


Neutral Ruthenium Carbene Complexes bearing N,N,O Heteroscorpionate Ligands: Syntheses and Activity in Metathesis Reactions

H. Kopf, B. Holzberger, C. Pietraszuk, E. Hübner, N. Burzlaff Organometallics 2008, 27, 5894 – 5905.
DOI: 10.1021/om8006129 (Link auf die Seite der Zeitschrift)

Neutral Fischer-type ruthenium(II) aminocarbene complexes bearing the bis(3,5-dimethylpyrazol-1-yl)acetato (bdmpza) ligand have been synthesized by addition of ammonia or methylamine to the α-carbon atom of vinylidene and allenylidene complexes. Reaction with dimethylamine was not successful. These differences in the chemical behavior can be explained by the intermediate formation of intramolecular hydrogen bridges that have been indicated by DFT calculations. Furthermore, octahedral ruthenium(II) benzylidene complexes with the bis(pyrazol-1-yl)acetato (bpza) and the bdmpza ligand were obtained by reacting [RuCl2(=CHPh)PR3)2] (R = Cy, Ph) with K[bpza] or K[bdmpza], respectively. The latter complexes have successfully been tested for RCM reactions.


Ruthenium Carbene, Vinylidene, and Allenylidene Complexes with a Bis(3,5-dimethylpyrazol-1-yl)acetato Heteroscorpionate Ligand

H. Kopf, C. Pietraszuk, E. Hübner, N. Burzlaff Organometallics 2006, 25, 2533 – 2546.
DOI: 10.1021/om060050y (Link auf die Seite der Zeitschrift)

A series of neutral ruthenium(II) carbonyl, carbene, vinylidene, and allenylidene complexes [Ru(bdmpza)(Cl)(L)(PPh3)] (L = C(OR‘)R, C=CHR, C=C=CR2, CO) containing the bis(3,5-dimethylpyrazol-1-yl)acetato (bdmpza) ligand, an N,N,O heteroscorpionate ligand, have been prepared. Treatment of [Ru(bdmpza)(Cl)(PPh3)2] (1a) with a variety of alkynes HC≡CR (R = Ph, Tol, Pr, Bu) afforded the vinylidene complexes Ru(bdmpza)(Cl)(=C=CHR)(PPh3)] (2a-d). The carbonyl complex [Ru(bdmpza)(Cl)(CO)(PPh3)] (3) is formed via oxidative or acid-induced degradation pathways from the vinylidene complexes. Reaction of 1a with the hydroxy-functionalized alkynes HC≡C(CH2)nOH (n = 2, 3) yielded the cyclic Fischer type carbene complexes [Ru(bdmpza)(Cl)(=C(CH2)3O)(PPh3)] (4a) and [Ru(bdmpza)(Cl)(=C(CH2)4O)(PPh3)] (4b). The ruthenium(II) allenylidene complexes [Ru(bdmpza)(Cl)(=C=C=CR2)(PPh3)] (5a, R = Ph; 5b, R = Tol) were prepared by the reaction of 1a with propargyl alcohols HC≡CC(R)2OH via the vinylidene intermediates [Ru(bdmpza)(Cl)(=C=CHCR2OH)(PPh3)]. X-ray crystal structures of one structural isomer of the vinylidene complex [Ru(bdmpza)(Cl)(=C=CHTol)(PPh3)] (2b), the carbonyl complex [Ru(bdmpza)(Cl)(CO)(PPh3)] (3), the carbene complex [Ru(bdmpza)(Cl)(=C(CH2)4O)(PPh3)] (4b-I), and two structural isomers of [Ru(bdmpza)(Cl)(=C=C=CPh2)(PPh3)] (5a-I and 5a-II) are reported.


Bis(pyrazol-1-yl)acetato Ligands in Ruthenium Chemistry: Syntheses and Structures of Ruthenium(II) and Ruthenium(III) Complexes with bpza and bdmpza

A. López-Hernández, R. Müller, H. Kopf, N. Burzlaff Eur. J. Inorg. Chem. 2002, 671 – 677.
DOI: 10.1002/1099-0682(200203)2002:3<671::AID-EJIC671>3.0.CO;2-V (Link auf die Seite der Zeitschrift)

New ruthenium(II) and ruthenium(III) complexes with the ligands bis(pyrazol-1-yl)acetate (bpza) and bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza) are reported. The reaction of ruthenium trichloride hydrate, H[bpza], and excess PPh3 yielded [Ru(bpza)Cl(PPh3)2] as a racemic mixture of an unsymmetrical isomer with traces of a symmetrical isomer. Similar reaction conditions using the more bulky H[bdmpza] yielded [Ru(bdmpza)Cl2(PPh3)]. Reaction of K[bpza] with [RuCl2(PPh3)3] offered a second route to [Ru(bpza)Cl(PPh3)2]. Also, [Ru(bdmpza)Cl(PPh3)2] was accessed by this synthetic approach. All three new complexes were characterized by X-ray structure determination.


Neutral Ruthenium(II) Carbene, Vinylidene and Allenylidene Complexes bearing the Ligands bpza or bdmpza

Henning Kopf, Nicolai Burzlaff – Posterpräsentation im Rahmen der „XXXVth International Conference on Coordination Chemistry“ (ICCC35), Heidelberg 2002, Germany. Abstract. Nr. P3.041 (S. 463).

Synthesis of new neutral ruthenium(II) complexes bearing the tripodal ligands bis(pyrazol-1-yl)acetate (bpza) or bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza) are described. The complexes are containing carben, vinyliden or allenyliden ligands. The carben complexes [RuLCl(PCy3)(=CHPh)] (L = bpza (1a), bdmpza (1b)) are prepared by the reaction of K[bpza] or K[bdmpza] with [RuCl2(PCy3)2(=CHPh)]. Synthesis of the vinyliden complexes [Ru(bdmpza)Cl(PPh3)(=C=CHR)] (2) is achieved by treating [Ru(bdmpza)ClPPh3)2] with 1-alkynes. Allenyliden complexes [Ru(bdmpza)Cl(PPh3)(=C=C=CR2)] (3) are prepared in similar manner starting with substituted 2-propyn-1-ols. The constitution of the complexes which might be precursors for future metathesis catalysts is discussed according to their X-ray structures and 2-dimensional NMR spectra.