Disilene // (systematically named disilicon tetrahydride) is an inorganic compound with the chemical formula Si
4. The name disilene, referring to the structure of a particular prototropic tautomer of the molecule. It is the simplest silene.
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|Molar mass||60.2028 g mol−1|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Disilene is a molecule with one Si=Si bond, and four equivalent Si-H bonds.
Unlike ethylene, disilene is kinetically unstable with respect to tautomerisation. Disilene has two other tautomers, that are very close in energy: (μ2-H)disilene, and disilanylidene.
Disilenes bearing sterically bulky substituents are isolable and have been well characterized although they remain mainly of academic interest. The first stabilised disilene was tetramesityldisilene, (C6Me3H2)4Si2. The Si=Si distance in this molecule is 2.15 Å, about 10% shorter than a typical Si–Si single bond. The Si2C4 core is roughly planar. Such species are typically prepared by reduction of organosilicon halides:
In one study a disilene is prepared by an intramolecular coupling of a 1,1-dibromosilane with potassium graphite. The silicon double bond in the resulting compound has a bond length of 227 picometer (second largest ever found) with trans-bent angles 33° and 31° (by X-ray diffraction).
In addition to this the substituents around the Si-Si bond are twisted by 43°. The disilene isomerizes to a tetracyclic compound by heating at 110°C in xylene thereby releasing its strain energy[clarification needed].