C=C/C=C-Metathese und Polyin-Kettenverlängerung in Metall-Koordinationssphären
Zusammenfassung der Projektergebnisse
Conditions and substrates for intramolecular ring-closing alkene metatheses in metal coordination spheres have been systematically optimized, particularly for complexes with trans phosphine ligands that contain one or more (CH2)nCH=CH2 substituents. Square planar pentafluorophenyl platinum complexes with trans Ph2P(CH2)nCH=CH2 ligands afford high yields of thirteen- to twenty-three-membered monomacrocycles with no apparent upper bound to ring size. Analogs with PhP((CH2)nCH=CH2)2 ligands afford dimacrocycles in fair to poor yields, but with good selectivites for interligand vs. inraligand metathesis. However, analogs with P((CH2)nCH=CH2)3 ligands afford oligomeric or incompletely cyclized products. Several strategies have been developed that afford trimacrocyclic three-fold intramolecular, interligand metathesis products from species with trans P((CH2)nCH=CH2)3 ligands. First, trigonal bipyramidal Fe(CO)3 adducts - which are believed to be conformationally pre- ( T organized for cyclization - afford the target complexes trans-Fe(CO)3(P((CH2)2n+2)3P (50- 74%), with no apparent upper bound to ring size. Second, square planar PtCl2, PdCl2, and Rh-(CO)Cl adducts afford ca. 40% yields of analogous species in the case of seventeen-membered macrocycles, but lower yields with larger macrocycles, and <1% yields with smaller macrocycles; there are no preorganizational factors, and larger ancillary ligands such as pentafluorophenyl must be avoided. Extensions to triarylphosphines with p-O(CH2)nCH=CH2 moieties give twenty-five to twenty-seven membered macrocycles. Substitution and addition reactions of all of these species have been explored. The preceding complexes have symmetries and connectivities that resemble toy gyroscopes. When the macrocycles are large enough, the ancillary ligands MLy can rotate by 360°. Barriers can be measured by NMR. Many crystal structures have been determined, and the feasibility of rotation can be estimated from intramolecular distances. Rotational barriers can be reversibly modulated via gaseous ligands, and irreversibly braked by the introduction of larger ligands. Our data have been highlighted in the popular literature (see (a) Chemical & Engineering News, 6 September 2004; (b) "Fast wie ein Kinderkreisel", Frankfurter Allgemeine Zeitung, 8 November 2004). We have also shown that similar alkyne metatheses can be effected in metal coordination spheres. However, they have only been used to prepare monomacrocycles to date. In a separate effort, we have been able to develop new strategies for polyyne synthesis that are applicable to a large family of Pt(C=C)nPt complexes, PtCxPt. The highest homologs in this series, PtC24Pt and PtC28Pt, exhibit excellent thermal stabilities (decomposition >140 °C), unlike analogs with organic endgroups. They provide the best models to date for the labile and poorly characterized polymeric sp carbon allotrope carbyne - the one dimensional analog of the classic polymeric sp2 and sp3 allotropes, graphite and diamond. Many properties of carbyne can be extrapolated from our data. There is every reason to believe that our methodology (iterative cross couplings followed by oxidative homocouplings under carefully controlled conditions) will be applicable to complexes with still longer sp carbon chains.
Projektbezogene Publikationen (Auswahl)
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"Alkene Metatheses in Transition Metal Coordination Spheres: Dimacrocyclizations that join trans Positions of Square-Planar Platinum Complexes to give Topologically Novel Diphosphine Ligands". Dalton Transactions 2004, 1012-1018
Shima, T.; Bauer, E. B.; Hampel, F.; Gladysz, J. A.
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"Alkyne Metatheses in Transition Metal Coordination Spheres: Convenient Tungstenand Molybdenum-Catalyzed Syntheses of Novel Metallamacrocycles". Adv. Synth. Catal. 2004,346,812-822
Bauer, E. B.; Hampel, F.; Glaydsz, J. A.
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"Molecular Gyroscopes: Fe(CO)3 and Fe(CO)2(NO)+ Rotators Encased in Three-Spoke Stators; Facile Assembly via Alkene Metatheses". Angew. Chem., Int. Ed. 2004,43,5537-5540
Shima, T.; Hampel, F.; Gladysz, J. A.
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"Molekulare Gyroskope: Fe(CO)3- und Fe(CO)2(NO)+-Rotatoren in einem Stator aus drei Speichen; Einfache Synthese durch Alken-Metathese". Angew. Chem. 2004,116, 5653-5656
Shima, T.; Hampel, F.; Gladysz, J. A.
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"A Synthetic Breakthrough into an Unanticipated Stability Regime: Readily Isolable Complexes in which C16-C28 Polyynediyl Chains Span Two Platinum Atoms". J. Am. Chem. Soc. 2005, 727,10508-10509
Zheng, Q.; Gladysz, J. A.
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"'Giant' Gyroscope-Like Molecules Consisting of Dipolar Cl-Rh-CO Rotators Encased in Three-Spoke Stators That Define 25-27 Membered Macrocycles". Angew. Chem., Int. Ed. Engl. 2006,45,4372-4375
Wang, L.; Hampel, F.; Gladysz, J. A.
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"A Synthetic Breakthrough into an Unanticipated Stability Regime: A Series of Isolable Complexes in which C6, C8, C10, C12, C16, C20, C24, and C28 Polyynediyl Chains Span Two Platinum Atoms". Chem. Eur. J. 2006, 72,6486-6505
Zheng, Q.; Bohling, J. C.; Peters, T. B.; Frisch, A. C.; Hampel, F.; Gladysz, J. A.
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"Generation of trans-Spanning Diphophine Ligands via Alkene Metathesis: Synthesis, Structure, and Dynamic Behavior of a Missing Link in a Series of Square-Planar Platinum Complexes". J. Mol. Catal. A. 2006,254, 20-28
Lewanzik, N.; Oeser, T.; Blümel, J.; Gladysz, J. A.
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"Gyroscope-Like Molecules Consisting of PdX2/PtX2 Rotators Encased in Three- Spoke Stators: Synthesis via Alkene Metathesis, and Facile Substitution and Demetallation Reactions", Nawara, A. J.; Shima, T.; Hampel, F.; Gladysz, J. A. J. Am. Chem. Soc. 2006,128,4962-4963
Nawara, A. J.; Shima, T.; Hampel, F.; Gladysz, J. A.
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"Gyroscope-Like Molecules Consisting of Three-Spoke Stators that Enclose "Switchable" Neutral Dipolar Rhodium Rotators; Reversible Cycling between Faster and Slower Rotating Rh(CO)I and Rh(CO)2I Species". Chem. Commun. 2006,4075-4077
Wang, L.; Shima, T. Hampel, F.; Gladysz, J. A.
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'"Gyroskop-Giganten': Dipolare Cl-Rh-CO-Rotatoren, umgeben von Statoren aus drei Speichen 25- bis 27-gliedriger Makrocyclen". Angew. Chem. 2006,118,4479-4482
Wang, L.; Hampel, F.; Gladysz, J. A.
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"Gyroscopes and the Chemical Literature: 1852-2002". Coord. Chem. Rev. 2007,251,1723-1733
Skopek, K.; Hershberger, M. M.; Gladysz, J. A.
