Tetrahedrane

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Tetrahedrane
Ball and stick model of tetrahedrane
Names
Preferred IUPAC name
Tricyclo[1.1.0.02,4]butane
Identifiers
3D model (
JSmol
)
2035811
ChEBI
ChemSpider
  • InChI=1S/C4H4/c1-2-3(1)4(1)2/h1-4H checkY
    Key: FJGIHZCEZAZPSP-UHFFFAOYSA-N checkY
  • C12C3C1C23
Properties
C4H4
Molar mass 52.076 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Tetrahedrane is a hypothetical

white phosphorus
.

Organic tetrahedranes

In 1978, Günther Maier prepared tetra-tert-butyl-tetrahedrane.

IUPAC name
tricyclo[1.1.0.02,4]butane.

Unsubstituted tetrahedrane (C4H4) remains elusive, although it is predicted to be kinetically stable. One strategy that has been explored (but thus far failed) is reaction of

propene with atomic carbon.[2] Locking away a tetrahedrane molecule inside a fullerene has only been attempted in silico.[3] Due to its bond strain and stoichiometry, tetranitrotetrahedrane has potential as a high-performance energetic material (explosive).[4] Some properties have been calculated based on quantum chemical methods.[5]

Tetra-tert-butyltetrahedrane

This compound was first synthesised starting from a

bromination, followed by addition of the fourth t-Bu group. Photochemical cheletropic elimination of carbon monoxide of the cyclopentadienone gives the target. Heating tetra-tert-butyltetrahedrane gives tetra-tert-butylcyclobutadiene. Though the synthesis appears short and simple, by Maier's own account, it took several years of careful observation and optimization to develop the correct conditions for the challenging reactions to take place. For instance, the synthesis of tetrakis(t-butyl)cyclopentadienone from the tris(t-butyl)bromocyclopentadienone (itself synthesized with much difficulty) required over 50 attempts before working conditions could be found.[7] The synthesis was described as requiring "astonishing persistence and experimental skill" in one retrospective of the work.[8] In a classic reference work on stereochemistry, the authors remark that "the relatively straightforward scheme shown [...] conceals both the limited availability of the starting material and the enormous amount of work required in establishing the proper conditions for each step."[9]

Tetra-tert-butyl-tetrahedrane synthesis 1978

Eventually, a more scalable synthesis was conceived, in which the last step was the photolysis of a cyclopropenyl-substituted diazomethane, which affords the desired product through the intermediacy of tetrakis(tert-butyl)cyclobutadiene:[10][11] This approach took advantage of the observation that the tetrahedrane and the cyclobutadiene could be interconverted (uv irradiation in the forward direction, heat in the reverse direction).

Tetra-tert-butyl-tetrahedrane synthesis 1991


Tetrakis(trimethylsilyl)tetrahedrane

Tetrakis(trimethylsilyl)tetrahedrane is relatively stable

Tetrakis(trimethylsilyl)tetrahedrane can be prepared by treatment of the cyclobutadiene precursor with

°C
concomitant with rearrangement to the cyclobutadiene, tetrakis(trimethylsilyl)tetrahedrane, which melts at 202 °C, is stable up to 300 °C, at which point it cracks to bis(trimethylsilyl)acetylene.

The tetrahedrane skeleton is made up of

picometers
.

Reaction with

Coupling reactions with this lithium compound gives extended structures.[15][16][17]

A bis(tetrahedrane) has also been reported.[18] The connecting bond is even shorter with 143.6 pm. An ordinary carbon–carbon bond has a length of 154 pm.

Synthesis of tetrakis(trimethylsilyl)tetrahedrane and its dimer.

Tetrahedranes with non-carbon cores

In tetrasilatetrahedrane features a core of four

NMR timescale due to migrations of the silyl substituents over the cage.[19]

Tetrasilatetrahedrane

The dimerization reaction observed for the carbon tetrahedrane compound is also attempted for a tetrasilatetrahedrane.

cluster compound
which can be described as a Si2 dumbbell (length 229 pm and with inversion of tetrahedral geometry) sandwiched between two almost-parallel Si3 rings.

Silicon cluster compound

In eight-membered clusters of in the same carbon group, tin Sn8R6 and germanium Ge8R6 the cluster atoms are located on the corners of a cube.

Inorganic and organometallic tetrahedranes

Structure of [InC(tms)3]4, a tetrahedrane with an In4 core (dark gray = In, orange = Si).[21]
Metal clusters that have tetrahedral cores are often called tetrahedranes.

The tetrahedrane motif occurs broadly in chemistry.

yellow arsenic (As4) are examples. Several metal carbonyl clusters are referred to as tetrahedranes, e.g. tetrarhodium dodecacarbonyl
.

Metallatetrahedranes with a single metal (or phosphorus atom) capping a cyclopropyl trianion also exist.[22]

See also

References

  1. doi:10.1002/anie.197805201
    .
  2. PMID 16933255
    .
  3. PMID 18993098
    .
  4. doi:10.1016/j.theochem.2003.10.054
    .
  5. PMID 15730286
    .
  6. doi:10.1016/S0040-4039(01)84500-7
    .
  7. doi:10.1002/cber.19811141218
    .
  8. OCLC 314371890
    .
  9. OCLC 27642721.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link
    )
  10. ISSN 0040-4039
    .
  11. doi:10.1055/s-2006-926404
    .
  12. doi:10.1002/hc.20699
    .
  13. PMID 12431112
    .
  14. PMID 14558797
    .
  15. PMID 19226138
    .
  16. PMID 21728313
    .
  17. S2CID 30151404
    .
  18. PMID 16041816
    .
  19. PMID 14583007
    .
  20. PMID 16287188
    .
  21. doi:10.1016/0022-328X(95)05399-A
    .
  22. ^
    • Organometallics 2019, 38, 21, 4054–4059.
    • Organometallics 1984, 3, 1574−1583.
    • Organometallics 1986, 5, 25−33.
    • J. Am. Chem. Soc. 1984, 106, 3356−3357.
    • J. Chem. Soc., Chem. Commun. 1984, 485−486.
    • Science Advances 25 Mar 2020: Vol. 6, no. 13, doi:10.1126/sciadv.aaz3168
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