Cyclobutadieneiron Tricarbonyl Annelated with Homoadamantene Frameworks

Minegishi, Shinya; Komatsu, Kôichi; Kitagawa, Toshikazu

doi:10.1021/om101054d

Cited by 7 publications

(5 citation statements)

References 74 publications

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“…[32][33][34] These considerations inspired us to design unprecedented experiments in which the G 4 C system was used as a host protective matrix for the synthesis of Me 2 CBD in aqueous solution. Previous or very recent results showed that cyclobutadiene, [25] cyclobutadieneiron-tricarbonyl, [35] or tetrasilacyclobutadiene [36] can be stabilized within a highly protective hydrophobic environment of bulky hydrocarboneous substituents, allowing crystallographic characterization. Herein, of very special interest is the stability of the parent Me 2 CBD and its unperturbed precursors Me 2 2 and Me 2 3 under protection of the G 4 C matrix.…”

Section: Resultsmentioning

confidence: 99%

Unprecedented Synthesis of 1,3‐Dimethylcyclobutadiene in the Solid State and Aqueous Solution

Legrand

Gilles

Petit

et al. 2011

Chemistry A European J

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Cyclobutadiene (CBD), the smallest cyclic hydrocarbon bearing conjugated double bonds, has long intrigued chemists because of its chemical characteristics. The question of whether the molecule could be prepared at all has been answered, but the parent compound and its unperturbed derivatives have eluded crystallographic characterization or synthesis "in water". Different approaches have been used to generate and to trap cyclobutadiene in a variety of confined environments: a) an Ar matrix at cryogenic temperatures, b) a hemicarcerand cage enabling the characterization by NMR spectroscopy in solution, and c) a crystalline guanidinium-sulfonate-calixarene G(4)C matrix that is stable enough to allow photoreactions in the solid state. In the latter case, the 4,6-dimethyl-α-pyrone precursor, Me(2)1, has been immobilized in a guanidinium-sulfonate-calixarene G(4)C crystalline network through a combination of non-covalent interactions. UV irradiation of the crystals transforms the entrapped Me(2)1 into a 4,6-dimethyl-Dewar-β-lactone intermediate, Me(2)2, and rectangular-bent 1,3-dimethylcyclobutadiene, Me(2)CBD(R), which are sufficiently stable under the confined conditions at 175 K to allow a conventional structure determination by X-ray diffraction. Further irradiation drives the reaction towards Me(2)3&Me(2)CBD(S)/CO(2) (63.7 %) and Me(2)CBD(R) (37.3 %) superposed crystalline architectures and the amplification of Me(2)CBD(R). The crystallographic models are supported by additional FTIR and Raman experiments in the solid state and by (1)H NMR spectroscopy and ESI mass spectrometry experiments in aqueous solution. Amazingly, the 4,6-dimethyl-Dewar-β-lactone, Me(2)2, the cyclobutadiene-carboxyl zwitterion, Me(2)3, and 1,3-dimethylcyclobutadiene, Me(2)CBD, were obtained by ultraviolet irradiation of an aqueous solution of G(4)C{Me(2)1}. 1,3-Dimethylcyclobutadiene is stable in water at room temperature for several weeks and even up to 50 °C as demonstrated by (1)H NMR spectroscopy.

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Section: Resultsmentioning

confidence: 99%

Unprecedented Synthesis of 1,3‐Dimethylcyclobutadiene in the Solid State and Aqueous Solution

Legrand

Gilles

Petit

et al. 2011

Chemistry A European J

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“…In contrast to the metal olefin π complexes, in cyclobutadiene (Cb) iron complexes, Fe-3d electrons are involved in conjugation with two lone pairs of the Cb ring and impart a 6-π-electron metallaromaticity. ,, Consequently, Cb metal complexes are more stable than Cp/diene analogues . Furthermore, functionalization of the cyclic π-systems with Cb (SiMe 3 ) 4 , Cb (Admantyl) 2 , Cb (Ph,TMS) 2 , and Cb Fc 2 substituents altered the steric and electronic properties of the cyclobutadiene ligands and their tricarbonyl iron complexes. Accordingly, expanding the π-systems of Cb ligands might enhance the integration of the half-sandwich structures of CbFe(CO) 3 .…”

Section: Introductionmentioning

confidence: 99%

Triazine-Augmented Catalytic Activity of Cyclobutadiene Tricarbonyl Fe(0) Complexes for Thermal Decomposition of Ammonium Perchlorate

et al. 2023

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The employment of combustion catalysts is an effective way to improve ammonium perchlorate (AP) decomposition performance during the combustion process of composite solid propellants. A classic half-sandwich iron carbonyl complex was proposed as the leading structure for exploring high-performance combustion catalysts, in which functionalized cyclobutadienes (Cb) tune the thermal stability and catalytic activity. The thermolysis of Fe2(CO)9 and substituted alkynes initiated [2 + 2] cyclization of alkyne triple bonds and gave η4-cyclobutadiene iron(0) tricarbonyl complexes, CbR1,R2-Fe-CO (1–6), with decent yields. A molecular structure analysis found that the conjugation of the aromatic substituents aryl, ferrocenyl (Fc), and triazinyl (Tz) finely tuned the coordination bonds around the Fe(0) center. The DSC/TG experiments found a remarkable thermal stability of CbTz,R-Fe-CO (3–6) with characteristic thermolysis temperatures (CTT) as high as 500 °C. The catalytic experiments demonstrated that the CTT of Cb-Fe-CO (2-6) overlapped with AP high-temperature decomposition (HTD). The thermal cross-coupling of HTD of AP and CTT of CbTz,Fc-Fe-CO (6) significantly augmented catalytic AP decomposition, resulting in a maximum energy release as high as 2828 J/g.

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“…Neutral IV decomposes upon oxidation under loss of C 4 H 4 [16] but bulky electron‐donating substituents in the ring, which lower ν CO up to 30 cm −1 , allow to stabilize the oxidized products. [17] …”

Section: Introductionmentioning

confidence: 99%

Bis(imidazolium)‐1,3‐diphosphete‐diide: A Building Block for FeC₂P₂ Complexes and Clusters

et al. 2022

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Reaction of the 6π-electron aromatic fourmembered heterocycle (IPr) 2 C 2 P 2 (1) (IPr = 1,3-bis(2,6diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene) with [Fe 2 CO 9 ] gives the neutral iron tricarbonyl complex [Fe(CO) 3 -η 3 -{(IPr) 2 C 2 P 2 }] (2). Oxidation with two equivalents of the ferrocenium salt, [Fe(Cp) 2 ](BArF 24 ), affords the dicationic tricarbonyl complex [Fe(CO) 3 -η 4 -{(IPr) 2 C 2 P 2 }](BArF 24 ) 2 (4). The one-electron oxidation proceeds under concomitant loss of one CO ligand to give the paramagnetic dicarbonyl radical cation complex [Fe(CO) 2 -η 4 -{(IPr) 2 C 2 P 2 }](BArF 24 ) (5). Reduction of 5 allows the preparation of the neutral dicarbonyl complex [Fe(CO) 2 -η 4 -{(IPr) 2 C 2 P 2 }] ( 6). An analysis by various spectroscopic techniques ( 57 Fe Mössbauer, EPR) combined with DFT calculations gives insight into differences of the electronic structure within the members of this unique series of iron carbonyl complexes, which can be either described as electron precise or Wade-Mingos clusters.

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Cyclobutadieneiron Tricarbonyl Annelated with Homoadamantene Frameworks

Cited by 7 publications

References 74 publications

Unprecedented Synthesis of 1,3‐Dimethylcyclobutadiene in the Solid State and Aqueous Solution

Unprecedented Synthesis of 1,3‐Dimethylcyclobutadiene in the Solid State and Aqueous Solution

Triazine-Augmented Catalytic Activity of Cyclobutadiene Tricarbonyl Fe(0) Complexes for Thermal Decomposition of Ammonium Perchlorate

Bis(imidazolium)‐1,3‐diphosphete‐diide: A Building Block for FeC₂P₂ Complexes and Clusters

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Cyclobutadieneiron Tricarbonyl Annelated with Homoadamantene Frameworks

Cited by 7 publications

References 74 publications

Unprecedented Synthesis of 1,3‐Dimethylcyclobutadiene in the Solid State and Aqueous Solution

Unprecedented Synthesis of 1,3‐Dimethylcyclobutadiene in the Solid State and Aqueous Solution

Triazine-Augmented Catalytic Activity of Cyclobutadiene Tricarbonyl Fe(0) Complexes for Thermal Decomposition of Ammonium Perchlorate

Bis(imidazolium)‐1,3‐diphosphete‐diide: A Building Block for FeC2P2 Complexes and Clusters

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Bis(imidazolium)‐1,3‐diphosphete‐diide: A Building Block for FeC₂P₂ Complexes and Clusters