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Günther Maier - One of the best experts on this subject based on the ideXlab platform.
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Tetrakis(trimethylsilyl)Tetrahedrane.
Journal of the American Chemical Society, 2002Co-Authors: Günther Maier, Akira Sekiguchi, Masanobu Tanaka, Jörg Neudert, Oliver Wolf, Dirk Pappusch, Tsukasa MatsuoAbstract:Tetrakis(trimethylsilyl)Tetrahedrane 3 has been synthesized upon irradiation of tetrakis(trimethylsilyl)cyclobutadiene 8, which can be prepared either by thermal nitrogen elimination from trimethylsilyl[1,2,3-tris(trimethylsilyl)-2-cycloprop-1-enyl]diazomethane 7 or by mild oxidation of cyclobutadiene dianion 9 with 1,2-dibromoethane. The structural characterization of Tetrahedrane 3 has been achieved by X-ray crystallography. The surprising thermal stability of 3 − which is stable up to 300 °C − is discussed.
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Electrochemical oxidation of two silyl-substituted Tetrahedranes
Tetrahedron Letters, 1996Co-Authors: Bo Hong, Günther Maier, Marye Anne Fox, Christian HermannAbstract:Abstract The electrochemical oxidations of tri-tert-butyl(trimethylsilyl)Tetrahedrane (1b) and tri-tert-butyl(isopropoxydimethylsilyl)Tetrahedrane (1c) were studied by cyclic voltammetry. Irreversible one-electron oxidations at Epa = +0.40 V and +0.43 V for 1b and 1c, respectively, were observed. The subsequent rearrangements of the radical cations of Tetrahedranes 1b and 1c to the corresponding radical cations of cyclobutadienes 2b and 2c were fast on a cyclic voltammetric timescale.
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Kleine Ringe, 90. Peralkyl‐substituierte Tetrahedrane
Liebigs Annalen, 1995Co-Authors: Günther Maier, Frank Fleischer, Hans‐otto KalinowskiAbstract:Small Rings, 90. – Peralkyl-Substituted Tetrahedranes Photolysis of the diazo compounds 4a, b generates adaman-tyltri-tert-butylTetrahedrane (9a) and tri-tert-butylisopropylTetrahedrane (9b), and the corresponding cyclobutadienes 10a, b. In contrast to Tetrahedrane 9a, which results from an intramolecular addition in carbene 7a and also from photoisomerization of cyclobutadiene 10a, the only source for Tetrahedrane 9b is the cheletropic cycloaddition of the carbenic center to the cyclopropene double bond in the photochemically produced carbene 7b. Tetrahedrane 9b is remarkable in its kinetic and thermal instability, which is caused by the reduced „corset effect” in this compound. An additional access to this Tetrahedrane is possible via the diazomethanes 34A and 34B. The pyridazines 17b and 41, which are formed by thermolysis of the diazo compounds 4b, 34A and 34B lead to the azetes 19 and 43. Last but not least 17b and 41 are interesting molecules themselves because of their inherent chirality.
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kleine ringe 90 peralkyl substituierte Tetrahedrane
Liebigs Annalen, 1995Co-Authors: Günther Maier, Frank Fleischer, Hansotto KalinowskiAbstract:Small Rings, 90. – Peralkyl-Substituted Tetrahedranes Photolysis of the diazo compounds 4a, b generates adaman-tyltri-tert-butylTetrahedrane (9a) and tri-tert-butylisopropylTetrahedrane (9b), and the corresponding cyclobutadienes 10a, b. In contrast to Tetrahedrane 9a, which results from an intramolecular addition in carbene 7a and also from photoisomerization of cyclobutadiene 10a, the only source for Tetrahedrane 9b is the cheletropic cycloaddition of the carbenic center to the cyclopropene double bond in the photochemically produced carbene 7b. Tetrahedrane 9b is remarkable in its kinetic and thermal instability, which is caused by the reduced „corset effect” in this compound. An additional access to this Tetrahedrane is possible via the diazomethanes 34A and 34B. The pyridazines 17b and 41, which are formed by thermolysis of the diazo compounds 4b, 34A and 34B lead to the azetes 19 and 43. Last but not least 17b and 41 are interesting molecules themselves because of their inherent chirality.
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Kleine Ringe, 89. Eine alternative Synthese von Tetra‐tert‐butyltetrahedran
Liebigs Annalen, 1995Co-Authors: Günther Maier, Frank FleischerAbstract:Small Rings, 89. – An Alternative Synthesis of Tetra-tert-butylTetrahedrane Cyclopropenyldiazomethane 3 is an ideal precursor for tetra-tert-butylTetrahedrane (6). Both, photochemical and thermal decomposition of 3 lead to cyclobutadiene 7, which can be photoisomerized to Tetrahedrane 6. Tetra-tert-butylTetrahedrane (6) is also formed directly by a cheletropic cycloaddition of the carbenic center to the cyclopropene double bond in carbene 4. This is the first example for the synthesis of a Tetrahedrane, which does not occur via the corresponding cyclobutadiene. The formation of pyridazine 10 dominates the thermolysis of 3. Azete 12 is obtained both by photolysis as well as by thermolysis of Dewar-pyridazine 11, the irradiation product of 10.
Roland Boese - One of the best experts on this subject based on the ideXlab platform.
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Kleine Ringe, 79. Synthese und Eigenschaften neuer Silyl‐substituierter Cyclobutadiene und Tetrahedrane
Chemische Berichte, 1994Co-Authors: Günther Maier, Reinhard Wolf, Hans‐otto Kalinowski, Roland BoeseAbstract:Small Rings, 79[1]. — Synthesis and Properties of Novel Silyl-Substituted Cyclobutadienes and Tetrahedranes The cyclobutadienes 2b, d as well as the corresponding Tetrahedranes 3b, d have been prepared according to the “Masamune route” by starting from the diazo compounds 1b, d. Low-temperature 13CNMR measurements of the cyclobutadienes 2a, b, d lead to the first exact values of the barrier heights in the interconversion of the two rectangular forms of the cyclobutadienes. Fluorodesilylation of 3d probably proceeds via tri-tert-butylTetrahedrane (3h) and cyclobutadiene 2h and finally yields diketone 18. Reaction of Tetrahedrane 3d with LiAlH4 in boiling THF leads to Tetrahedrane 3e, which is much less stable than all previously known Tetrahedrane derivatives.
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kleine ringe 79 synthese und eigenschaften neuer silyl substituierter cyclobutadiene und Tetrahedrane
Chemische Berichte, 1994Co-Authors: Günther Maier, Reinhard Wolf, Hansotto Kalinowski, Roland BoeseAbstract:Small Rings, 79[1]. — Synthesis and Properties of Novel Silyl-Substituted Cyclobutadienes and Tetrahedranes The cyclobutadienes 2b, d as well as the corresponding Tetrahedranes 3b, d have been prepared according to the “Masamune route” by starting from the diazo compounds 1b, d. Low-temperature 13CNMR measurements of the cyclobutadienes 2a, b, d lead to the first exact values of the barrier heights in the interconversion of the two rectangular forms of the cyclobutadienes. Fluorodesilylation of 3d probably proceeds via tri-tert-butylTetrahedrane (3h) and cyclobutadiene 2h and finally yields diketone 18. Reaction of Tetrahedrane 3d with LiAlH4 in boiling THF leads to Tetrahedrane 3e, which is much less stable than all previously known Tetrahedrane derivatives.
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Kleine Ringe, 78. Tri‐tert‐butyl(trimethylsilyl)cyclobutadien und Tri‐tert‐butyl(trimethylsilyl)tetrahedran
Chemische Berichte, 1994Co-Authors: Günther Maier, Reinhard Wolf, Roland Boese, Dieter Born, Ines Bauer, Dieter CremerAbstract:Small Rings, 78[1]. - Tri-tert-butyl(trimethylsilyl)cyclobutadiene and Tri-tert-butyl(trimethylsilyl)Tetrahedrane The chemistry of diazo(1,2,3-tri-tert-butylcyclopropenyl)(trimethylsilyl)methane (6) is unexpectedly diverse. Upon irradiation it fragments exclusively into the acetylenes 7 and 8. Flash thermolysis, on the other hand, gives — aside from the two acetylenes — tri-tert-butylazete (10) and trimethylsilyl cyanide (11). Upon heating 6 presumably isomerizes via betaine 17 to Dewar-diazabenzene 13 — which is split into 10 and 11 — and diazabenzvalene 18. This reaction course is supported by the isolation of the carbonyliron complexes 15 and 16, — The CuCl-catalyzed thermal decomposition again follows a different route. Under these conditions tri-tert-butyl(trimethylsilyl)cyclobutadiene (5) is formed, probably as a weak CuCl complex. Only after addition of ethylenebis(diphenylphosphane) free cyclobutadiene 5 can be isolated. Upon irradiation of 5 a quantitative isomerization to tri-tert-butyl(trimethylsilyl)Tetrahedrane (29) occurs. This second, spectroscopically unequivocally confirmed Tetrahedrane melts at 179°C. In solution the isomerization to cyclobutadiene 5 starts at about 160°C. That means, it is thermally even more stable than tetra-tert-butylTetrahedrane.
Hans Schumann - One of the best experts on this subject based on the ideXlab platform.
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ubergangsmetall substituierte diphosphene xx1 synthese und eigenschaften des tetrahedrans η5 c5me5 co 2fep ptbu fe2 co 6 und der metallierten 1 3 diphospha 2 propanone η5 c5me5 co 2fe pc o pr fe2 co 6 r tbu 2 4 6 cf3 3c6h2
Chemische Berichte, 1991Co-Authors: Lothar Weber, Hans SchumannAbstract:Transition-Metal-Substituted Diphosphenes, XX1). – Synthesis and Properties of the Tetrahedrane [(η5-C5Me5)(CO)2-FeP–PtBu]Fe2(CO)6 and the Metalated 1,3-Diphospha-2-propanones [(η5-C5Me5)(CO)2Fe–PC(O)–PR]Fe2(CO)6 [R = tBu, 2,4,6-(CF3)3C6H2] The reaction of [η5-C5Me5)(CO)2FeP(SiMe3)2 (1) with tBuPCl2 (2a) affords the metalated cyclotetraphosphane [(η5-C5Me5)-(CO)2FeP–PtBu]2 (4a) besides the metal-substituted cyclotriphosphane (η5-C5Me5(CO)2Fe–P[PtBu]2 (5a) and the diphosphane (η5-C5Me5)(CO)2FeP(SiMe3)P(Cl)tBu (3a), which are detected in the reaction mixture by 31P-NMR spectroscopy. Treatment of 4a with excess of Fe2(CO)9 leads to the Tetrahedrane [(η5-C5Me5)(CO)2FeP–PtBu]Fe2(CO)6 (6a) and the 1,3-diphospha-2-propanone derivative [(η5-C5Me5)(CO)2FePC(O)-P–tBu]Fe2(CO)6 (7a). Similarily, an analogous complex 7c is obtained from the reaction of in situ prepared (η5-C5Me5)-(CO)2FePP–C6H2(CF3)3-(2,4,6) with an excess of Fe2(CO)9.
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Übergangsmetall‐substituierte Diphosphene, XX1) Synthese und Eigenschaften des Tetrahedrans [(η5‐C5Me5)(CO)2FeP–PtBu]Fe2(CO)6 und der metallierten 1,3‐Diphospha‐2‐propanone [(η5‐C5Me5)(CO)2Fe–PC(O)–PR]Fe2(CO)6 [R = tBu, 2,4,6‐(CF3)3C6H2]
Chemische Berichte, 1991Co-Authors: Lothar Weber, Hans SchumannAbstract:Transition-Metal-Substituted Diphosphenes, XX1). – Synthesis and Properties of the Tetrahedrane [(η5-C5Me5)(CO)2-FeP–PtBu]Fe2(CO)6 and the Metalated 1,3-Diphospha-2-propanones [(η5-C5Me5)(CO)2Fe–PC(O)–PR]Fe2(CO)6 [R = tBu, 2,4,6-(CF3)3C6H2] The reaction of [η5-C5Me5)(CO)2FeP(SiMe3)2 (1) with tBuPCl2 (2a) affords the metalated cyclotetraphosphane [(η5-C5Me5)-(CO)2FeP–PtBu]2 (4a) besides the metal-substituted cyclotriphosphane (η5-C5Me5(CO)2Fe–P[PtBu]2 (5a) and the diphosphane (η5-C5Me5)(CO)2FeP(SiMe3)P(Cl)tBu (3a), which are detected in the reaction mixture by 31P-NMR spectroscopy. Treatment of 4a with excess of Fe2(CO)9 leads to the Tetrahedrane [(η5-C5Me5)(CO)2FeP–PtBu]Fe2(CO)6 (6a) and the 1,3-diphospha-2-propanone derivative [(η5-C5Me5)(CO)2FePC(O)-P–tBu]Fe2(CO)6 (7a). Similarily, an analogous complex 7c is obtained from the reaction of in situ prepared (η5-C5Me5)-(CO)2FePP–C6H2(CF3)3-(2,4,6) with an excess of Fe2(CO)9.
Reinhard Wolf - One of the best experts on this subject based on the ideXlab platform.
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Kleine Ringe, 79. Synthese und Eigenschaften neuer Silyl‐substituierter Cyclobutadiene und Tetrahedrane
Chemische Berichte, 1994Co-Authors: Günther Maier, Reinhard Wolf, Hans‐otto Kalinowski, Roland BoeseAbstract:Small Rings, 79[1]. — Synthesis and Properties of Novel Silyl-Substituted Cyclobutadienes and Tetrahedranes The cyclobutadienes 2b, d as well as the corresponding Tetrahedranes 3b, d have been prepared according to the “Masamune route” by starting from the diazo compounds 1b, d. Low-temperature 13CNMR measurements of the cyclobutadienes 2a, b, d lead to the first exact values of the barrier heights in the interconversion of the two rectangular forms of the cyclobutadienes. Fluorodesilylation of 3d probably proceeds via tri-tert-butylTetrahedrane (3h) and cyclobutadiene 2h and finally yields diketone 18. Reaction of Tetrahedrane 3d with LiAlH4 in boiling THF leads to Tetrahedrane 3e, which is much less stable than all previously known Tetrahedrane derivatives.
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kleine ringe 79 synthese und eigenschaften neuer silyl substituierter cyclobutadiene und Tetrahedrane
Chemische Berichte, 1994Co-Authors: Günther Maier, Reinhard Wolf, Hansotto Kalinowski, Roland BoeseAbstract:Small Rings, 79[1]. — Synthesis and Properties of Novel Silyl-Substituted Cyclobutadienes and Tetrahedranes The cyclobutadienes 2b, d as well as the corresponding Tetrahedranes 3b, d have been prepared according to the “Masamune route” by starting from the diazo compounds 1b, d. Low-temperature 13CNMR measurements of the cyclobutadienes 2a, b, d lead to the first exact values of the barrier heights in the interconversion of the two rectangular forms of the cyclobutadienes. Fluorodesilylation of 3d probably proceeds via tri-tert-butylTetrahedrane (3h) and cyclobutadiene 2h and finally yields diketone 18. Reaction of Tetrahedrane 3d with LiAlH4 in boiling THF leads to Tetrahedrane 3e, which is much less stable than all previously known Tetrahedrane derivatives.
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Tri-tert-butyl(trimethylgermyl)cyclobutadien und Tri-tert-butyl(trimethylgermyl)tetrahedran
Chemische Berichte, 1994Co-Authors: Günther Maier, Reinhard Wolf, Hans‐otto KalinowskiAbstract:Small Rings, 80[1]. — Tri-tert-butyl(trimethylgermyl)cyclobutadiene and Tri-tert-butyl(trimethylgermyl)Tetrahedrane In the course of our research on silyl-substituted diazo compounds as precursors of cyclobutadienes and Tetrahedranes the synthesis of the title compounds 16 and 17 has also been accomplished. Their properties are comparable to those of the silyl-substituted homologous compounds. Tri-tert-butyl(trimethylgermyl)Tetrahedrane (17) melts without decomposition at 143°C and thus proves to be as stable as tri-tert-butyl(trimethylsilyl)Tetrahedrane. The interconversion of the rectangular forms of tri-tert-butyl(trimethylgermyl)cyclobutadiene (16) proceeds with an activation energy below 4 kcal/mol, which is nearly the same as of tri-tert-butyl(trimethylsilyl)cyclobutadiene.
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Kleine Ringe, 78. Tri‐tert‐butyl(trimethylsilyl)cyclobutadien und Tri‐tert‐butyl(trimethylsilyl)tetrahedran
Chemische Berichte, 1994Co-Authors: Günther Maier, Reinhard Wolf, Roland Boese, Dieter Born, Ines Bauer, Dieter CremerAbstract:Small Rings, 78[1]. - Tri-tert-butyl(trimethylsilyl)cyclobutadiene and Tri-tert-butyl(trimethylsilyl)Tetrahedrane The chemistry of diazo(1,2,3-tri-tert-butylcyclopropenyl)(trimethylsilyl)methane (6) is unexpectedly diverse. Upon irradiation it fragments exclusively into the acetylenes 7 and 8. Flash thermolysis, on the other hand, gives — aside from the two acetylenes — tri-tert-butylazete (10) and trimethylsilyl cyanide (11). Upon heating 6 presumably isomerizes via betaine 17 to Dewar-diazabenzene 13 — which is split into 10 and 11 — and diazabenzvalene 18. This reaction course is supported by the isolation of the carbonyliron complexes 15 and 16, — The CuCl-catalyzed thermal decomposition again follows a different route. Under these conditions tri-tert-butyl(trimethylsilyl)cyclobutadiene (5) is formed, probably as a weak CuCl complex. Only after addition of ethylenebis(diphenylphosphane) free cyclobutadiene 5 can be isolated. Upon irradiation of 5 a quantitative isomerization to tri-tert-butyl(trimethylsilyl)Tetrahedrane (29) occurs. This second, spectroscopically unequivocally confirmed Tetrahedrane melts at 179°C. In solution the isomerization to cyclobutadiene 5 starts at about 160°C. That means, it is thermally even more stable than tetra-tert-butylTetrahedrane.
Manfred L Ziegler - One of the best experts on this subject based on the ideXlab platform.
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darstellung und charakterisierung der Tetrahedrane cpm co 2 3p m mo w sowie der derivate cpmo co 2 3p mo co 5 und cpw co 2 3p w co 5
Chemische Berichte, 1995Co-Authors: Thomas Kilthau, Bernd Nuber, Manfred L ZieglerAbstract:Synthesis and Characterization of the Tetrahedranes [CpM(CO)2]3P (M = Mo, W) and Their Derivatives [CpMo(CO)2]3P–Mo(CO)5 and [CpW(CO)2]3P–W(CO)5 The reaction of Na[CpM(CO)3] (M = Mo, W) with PCl3 in diglyme yields the cluster compounds [CpMo(CO)2]3P–Mo(CO)5 (2a) and [CpW(CO)2]3P–W(CO)5 (2b) in good yields as well as the Tetrahedranes [CpMo(CO)2]3P (3a) and [CpW(CO)2]3P (3b) as side products. Compounds 3a, b are obtained independently by the reaction of 2a, b with PPh3. The clusters 2a, b and 3a, b were characterized spectroscopically (IR, NMR, MS), and X-ray structure determinations were carried out on 2a, b.
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Darstellung und Charakterisierung der Tetrahedrane [CpM(CO)2]3P (M = Mo, W) sowie der Derivate [CpMo(CO)2]3P‐Mo(CO)5 und [CpW(CO)2]3P–W(CO)5
Chemische Berichte, 1995Co-Authors: Thomas Kilthau, Bernd Nuber, Manfred L ZieglerAbstract:Synthesis and Characterization of the Tetrahedranes [CpM(CO)2]3P (M = Mo, W) and Their Derivatives [CpMo(CO)2]3P–Mo(CO)5 and [CpW(CO)2]3P–W(CO)5 The reaction of Na[CpM(CO)3] (M = Mo, W) with PCl3 in diglyme yields the cluster compounds [CpMo(CO)2]3P–Mo(CO)5 (2a) and [CpW(CO)2]3P–W(CO)5 (2b) in good yields as well as the Tetrahedranes [CpMo(CO)2]3P (3a) and [CpW(CO)2]3P (3b) as side products. Compounds 3a, b are obtained independently by the reaction of 2a, b with PPh3. The clusters 2a, b and 3a, b were characterized spectroscopically (IR, NMR, MS), and X-ray structure determinations were carried out on 2a, b.