Synthese, Struktur, Dynamik und Reaktivität gyroskopähnlicher Moleküle
Zusammenfassung der Projektergebnisse
We have subjected a variety of trigonal bipyramidal, square planar, and octahedral bis(phosphine) complexes of the formulae trans-LyM(P((CH2)nCH=CH2)3)2 to alkene metathesis/hydrogenation sequences. In a great many cases with n > 4, three-fold intramolecular and interligand ring closing metathesis occurs to give complexes of the type trans-LyM(P((CH2)2n+2)3P), which resemble toy gyroscopes in their symmetries and connectivities. Similar sequences have been conducted with alkene-containing triarylphosphines and trialkylphosphites, as well as pyridine complexes of the formula trans-LyM(2,6-NC5H3(CH2X(CH2)nCH=CH2)2. With triarylphosphines, up to 27 membered macrocycles can be synthesized. Despite the cage like environment, substitution reactions are easily effected at the metal. These usually proceed somewhat more slowly than model compounds lacking the cage. Many of these compounds are crystalline, and can be crystallographically characterized (with only minor disorder problems). Interestingly, when the rotator features only small ligands (CO, NO, Cl), rotation through 17 membered macrocycles (P(CH2)14P linkages) is rapid on the NMR time scale at room temperature. Only in the case of certain trigonal bipyramidal complexes, which for reasons of symmetry and ground vs. transition state strain exhibit higher rotational barriers, can decoalescence can be observed at low temperatures and barriers quantitatively determined. Rotation can be braked by introducing larger ligands. All of these results nicely correlate with crystallographic data, from which the radii of the rotators and the "clearance" offered by the gyroscope spokes can be estimated. In certain series of compounds, small amounts of byproducts derived from a combination of inter- and intraligand metathesis can be observed. When metathesis/hydrogenation sequences are conducted with analogous cis complexes, three fold intramolecular and intraligand ring closing metathesis can also be observed, giving what are termed "parachute" complexes. These do not equilibrate with isomeric gyroscope like complexes below 100 °C. Interestingly, certain nucleophiles can remove metals from the gyroscope cages, giving dibridgehead diphosphines with a host of fascinating properties. In collaborations with physicists, we have attempted to use rotating electric fields to effect unidirectional rotation of rotators with dipole moments, using dielectric spectroscopy as an assay technique.
Projektbezogene Publikationen (Auswahl)
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"Octahedral Gyroscope-Like Molecules with M(CO)3(X) Rotators Encased in Three- Spoked Diphosphine Stators: Syntheses by Alkene Metathesis/Hydrogenation Sequences, Structures, Dynamic Properties, and Reactivities", Organometallics 2007, 26, 5129-5131
Hess, G. D.; Hampel, F.; Gladysz, J. A.
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2007, "Synthesis of Gyroscope-like Molecules via Alkene Metathesis. Facile Substitution and Demetalation, and a Search for Cage Effects"
Agnieszka J. Nawara-Hultzsch
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"Syntheses of Gyroscope-Like Molecules via Three-Fold Ring Closing Metatheses of bis(Phosphine) Complexes trans-LyM(P((CH2)nCH=CH2)3)2, and Extensions to bis- (Phosphite) Complexes trans-Fe(CO)3(P(O(CH2)nCH=CH2)3)2", J. Organomet. Chem. 2008, 693, 857-866
Skopek, K.; Gladysz, J. A.
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"Three-Fold Intramolecular Ring-Closing Metatheses Involving Square Planar Platinum Complexes with cis Phosphorus Donor Ligands: Syntheses, Structures, and Properties of Parachute Like Complexes", Inorg. Chem. 2008, 47, 3474-3476
Skopek, K.; Hampel, F.; Gladysz, J. A.
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2008, "Alkene Metathesis: Applications in the Synthesis of Novel Organometallic Complexes, and Mechanistic Investigations"
Giovanni Pietro Rachiero
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2008, "Synthesis of Gyroscope- and Parachute-Like Molecules via Alkene Metathesis"
Katrin Skopek
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"Syntheses and Palladium, Platinum, and Borane Adducts of Symmetrical Trialkylphosphines with Three Terminal Vinyl Groups, P((CH2)mCH=CH2)3", Z. Naturforsch. B: Anorg. Chem., Org. Chem. 2010, 65, 414-424
Nawara-Hultzsch, A. J.; Skopek, K.; Shima, T.; Barbasiewicz, M.; Hess, G. D.; Skaper, D.; Gladysz, J. A.
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2010, "Syntheses and Dielectric Measurements of Symmetry Reduced Gyroscope-like Iron Complexes, and Syntheses of Octahedral Gyroscope-like Chromium and Molybdenum Complexes"
Dirk Skaper
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2010, "Syntheses of Rhenium Containing Gyroscope-like Complexes, and Related Species"
Gisela D. Hess
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2010, "Synthesis of Molecular Gyroscopes with Transition Metal Rotators and Related Complexes via Alkene and Alkyne Metathesis"
Esther Steigleder
