Tetrahedrane is a hypothetical platonic hydrocarbon with chemical formula and a tetrahedral structure. The molecule would be subject to considerable angle strain and has not been synthesized as of 2021. However, a number of derivatives have been prepared. In a more general sense, the term tetrahedranes is used to describe a class of molecules and ions with related structure, e.g. white phosphorus. Organic tetrahedranes In 1978, Günther Maier prepared tetra-tert-butyl-tetrahedrane. These bulky substituents envelop the tetrahedrane core. Maier suggested that bonds in the core are prevented from breaking because this would force the substituents closer together (corset effect) resulting in Van der Waals strain. Tetrahedrane is one of the possible platonic hydrocarbons and has the IUPAC name tricyclo[1.1.0.02,4]butane. Unsubstituted tetrahedrane () 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. Locking away a tetrahedrane molecule inside a fullerene has only been attempted in silico. Due to its bond strain and stoichiometry, tetranitrotetrahedrane has potential as a high-performance energetic material (explosive). Some properties have been calculated based on quantum chemical methods. Tetra-tert-butyltetrahedrane This compound was first synthesised starting from a cycloaddition of an alkyne with t-Bu substituted maleic anhydride, followed by rearrangement with carbon dioxide expulsion to a cyclopentadienone and its 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. The synthesis was described as requiring "astonishing persistence and experimental skill" in one retrospective of the work. 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." 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: This approach took advantage of the observation that the tetrahedrane and the cyclobutadiene could