Si4O11

Si4O11 is the chemical formula for a silicon oxide species that belongs to the broader family of condensed silicon-oxygen compounds. It can be viewed as a silicate-like oxide containing four silicon atoms interconnected by oxygen atoms, giving an overall ratio of eleven oxygens to four silicons. In silicate chemistry, silicon centers are typically tetrahedrally coordinated by oxygen (SiO4), and in condensed forms these tetrahedra share oxygens to build networks. For Si4O11, the connectivity would correspond to a particular arrangement of four SiO4 tetrahedra that accounts for 11 oxygen atoms, allowing for a mix of bridged and terminal oxygens. Because silicon-oxide networks can adopt multiple isomeric forms, there is no single universally accepted crystal structure for Si4O11 in the solid state; discrete Si4O11 units are more often described as parts of larger silicate frameworks or as transient gas-phase oligomers.

Occurrence and synthesis of Si4O11 are not tied to a distinct mineral species. It can arise as an intermediate or fragment in high-temperature silicate systems, during dehydration or condensation of silicate hydrates, or as a detected species in mass spectrometric or spectroscopic studies of silicon-oxide clusters. As a specific molecular oxide, its properties depend on the exact structural arrangement, and detailed data (density, melting point) are not typically established for a standalone Si4O11 solid.

See also: silicate oligomers, disilicate (Si2O7), tetrasilicate.