Silane - Properties

Properties

Silane is the silicon analogue of methane. Because of the greater electronegativity of hydrogen in comparison to silicon, in silane the hydrogen atoms have a partial negative charge and the silicon a positive charge. This Si-H bond polarity is the opposite of that observed in the C-H bonds of methane. However, the C-H bonds in methane are generally regarded as non-polar since carbon is only slightly more electronegative than hydrogen. At room temperature, silane is a gas, and is pyrophoric — it undergoes spontaneous combustion in air, without the need for external ignition. However, the difficulties in explaining the available (often contradictory) combustion data are ascribed to the fact that silane itself is stable and that the natural formation of larger silanes during production, as well as the sensitivity of combustion to impurities such as moisture and to the catalytic effects of container surfaces causes its pyrophoricity. Above 420 °C, silane decomposes into silicon and hydrogen; it can therefore be used in the chemical vapor deposition of silicon.

Silane has a sharp, repulsive smell, somewhat similar to that of acetic acid

Silane has recently been shown to act as a superconductor under extremely high pressures (96 and 120 GPa), with a transition temperature of 17 K.