Kleine Ringe, 38: Tetra‐<i>tert</i>‐butyltetrahedran

Maier, Günther; Pfriem, Stephan; Schäfer, Ulrich; Malsch, Klaus‐Dieter; Matusch, Rudolf

doi:10.1002/cber.19811141218

Cited by 113 publications

(20 citation statements)

References 56 publications

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“…Nonetheless the parent tetrahedral C 4 cage (mϭ1, nϭ0) already exists in saturated form as a tetrahedrane, C 4 R 4 , where R represents a bulky tertiobutyl substituent. 19 DFT calculations show that the smallest truncated tetrahedron C 12 is unstable, whereas higher networks such as C 48 and C 52 are stable which is in agreement with the expectation that the strain is less in larger cages. This makes them realistic targets for chemical synthesis.…”

Section: Discussionsupporting

confidence: 86%

Electronic structure of polyhedral carbon cages consisting of hexagons and triangles

et al. 2002

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An infinite series of ͑3,6͒ cages is defined by trivalent carbon polyhedra composed of hexagonal and four triangular rings. A zone-folding construction is applied to the graphene band structure to yield explicit expressions for the -molecular orbitals, energies, and symmetries of the cages that depend only on four indices m, n, p, and q. Leapfrog members of the series ͑mϪnϭ0 mod 3 and pϪqϭ0 mod 3͒ have closed shells in a neutral form with two filled nonbonding orbitals; all others have closed shells as dications. Quantum chemical calculations on C 12 , C 48 , and C 52 2ϩ confirm this result. Embedding relationships are proved for the spectra of ͑3,6͒ cages related by inflation transformations corresponding to stretching and rotation of the polyhedral net.

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Section: Discussionsupporting

confidence: 86%

Electronic structure of polyhedral carbon cages consisting of hexagons and triangles

et al. 2002

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“…From the data above, the antiaromatic destabilization energy (ADE) of cyclobutadiene can be derived from the definition illustrated in Equation (3). A value of (143 AE 16) kJ mol À1 is obtained, which is in good accord with G3…”

Section: Angewandte Chemiementioning

confidence: 82%

“…Room temperature stable derivatives such as tri-tert-butylcyclobutadiene [2] and tetra-tert-butylcyclobutadiene [3] were successfully prepared and spectroscopically characterized, whereas the parent compound was found to be more elusive. It dimerizes in solid matrices at !…”

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confidence: 99%

The Heat of Formation of Cyclobutadiene

et al. 2006

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Cyclobutadiene (1) and its derivatives have beckoned to chemists ever since Kekules deduction of the structure of benzene and his attempt to synthesize 1 in 1872.[1] Pioneering efforts by Willstätter and Finkelstein were followed by a century of studies which produced many remarkable findings. Room temperature stable derivatives such as tri-tert-butylcyclobutadiene [2] and tetra-tert-butylcyclobutadiene [3] were successfully prepared and spectroscopically characterized, whereas the parent compound was found to be more elusive. It dimerizes in solid matrices at ! 35 K, is a transient reactive intermediate in solution, and has a lifetime of only 2 ms at 0.1 Torr in the gas phase.[1a] Nevertheless, trapping [4] and spectroscopic results have revealed that cyclobutadiene has a ground-state singlet configuration and adopts a rectangular D 2h structure which rapidly undergoes automerization. An isolable and room temperature stable complex consisting of 1 in the cavity of a spherical crown ether (that is, a hemicarceplex) has even been prepared, [5] but the thermodynamic stability of cyclobutadiene remains experimentally unknown.Conventional calorimetric methods are precluded when it comes to cyclobutadiene and its simple derivatives because of their high reactivity. Electrochemical, [6] pK a , [7] and kinetic [8] measurements of model compounds have been carried out and interpreted as indicating that 1 has a negative resonance energy of at least 50-67 kJ mol À1 . This conclusion is in accord with many of the early computational findings and a

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“…25e,33 In 1978, Maier reported the synthesis of the first stable tetrahedrane 22 supported by four tert-butyl groups. 29d, 34 The so-called 'corset effect' by the accumulation of four bulky substituents may well be Very recently, we have found a better synthetic approach to tetrahedrane 23. CBD 14 reacted with a catalytic amount of B(C 6 F 5 ) 3 to give 23 in 30% isolated yield.…”

Section: Tetrahedranesmentioning

confidence: 99%

Doubly Charged Four-Membered Ring Systems: Cyclobutadiene Dianions and Heavy Cyclobutadiene Dianions

Sekiguchi¹,

Matsuo²

2006

Synlett

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Recent progress in the experimental chemistry of cyclobutadiene dianions (CBD 2s) containing a doubly charged fourmembered ring system is reviewed. New families of silyl-substituted CBD 2s, cyclobutadienes (CBDs), and tetrahedranes are covered in detail. The aromaticity of the tetrasilyl-and diphenyldisilyl-CBD 2s have been studied on the basis of structural characteristics and magnetic properties. All of the CBD 2s show a strong diatropic ring current resulting from six p-electron system. The preparation of CBD 2derivatives consisting of heavier group 14 elements (Si and Ge) is also included. They demonstrate a non-aromatic nature with a folded four-membered ring. Conclusion

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Kleine Ringe, 38: Tetra‐tert‐butyltetrahedran

Cited by 113 publications

References 56 publications

Electronic structure of polyhedral carbon cages consisting of hexagons and triangles

Electronic structure of polyhedral carbon cages consisting of hexagons and triangles

The Heat of Formation of Cyclobutadiene

Doubly Charged Four-Membered Ring Systems: Cyclobutadiene Dianions and Heavy Cyclobutadiene Dianions

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