Silicon monoxide

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Silicon monoxide
Identifiers
CAS number [10097-28-6 (solid)]
Properties
Molecular formula SiO
Molar mass 44.0850 g/mol
Appearance brown - black glassy solid
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Silicon monoxide is the chemical compound with the formula SiO. In the vapour phase it is a diatomic molecule.[1] It has been detected in stellar objects (e.g [2] [1])and it has been described as the most common oxide of silicon in the universe.[3]
When SiO gas is cooled rapidly it condenses to form a glassy brown/black amorphous solid which is available commercially and used to deposit films of SiO, which oxidize in air giving SiO2.[1]

Contents

[edit] Molecular SiO

When SiO2 is heated with silicon, gaseous SiO is produced[1]:

SiO2 + Si → SiO

Silica can be removed from ores or minerals by heating with silicon to produce gaseous SiO.[1]

Refractories containing SiO2 can be corroded by reduction with H2 or CO at high temperatures e.g.:[4]

SiO2 + H2 → SiO + H2O

SiO decomposes rapidly:[1]

2SiO → SiO2 + Si

[edit] Matrix isolated SiO

Silicon monoxide has been trapped in an argon matrix cooled by helium and the Si-O bond length determined from molecules trapped in argon matrix is 148.9 pm. [3] The bond length is similar to that in linear, molecular, SiO2 and there is no indication of a triple bond as in CO.[3]
SiO dimers, trimers and tetramers have been detected that all have (Si-O)n ring structures and contain no Si-Si bonds.[3]

SiO condensed with F2, Cl2 or COS, followed by irradiation with light, the planar molecules OSiF2,(Si-O 148 pm); OSiCl2, (Si-O 149 pm) and linear OSiS (SiO 149, SiS 190 pm are produced. [3]

SiO condensed with oxygen atoms generated by microwave discharge produces molecular SiO2 which has a linear structure.
When metal atoms are codeposited (i.e. Na, Al, Pd, Ag, Au) triatomic molecules are produced with linear, (AlSiO and PdSiO), non-linear (AgSiO and AuSiO), and ring (NaSiO) structures.[3]

[edit] Solid SiO

Recent work suggests that the commercially available solid form is best considered as an inhomogenous mixture of SiO2 and Si with evidence of bonding at the interface of the Si and SiO2 phases.[5] [6]

[edit] References

  1. ^ a b c d e Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0123526515
  2. ^ A survey of SiO 5 -> 4 emission towards outflows from massive young stellar objects, Gibb, A. G.; Davis, C. J.; Moore, T. J. T., Monthly Notices of the Royal Astronomical Society, 382, 3, 1213-1224,doi:10.1111/j.1365-2966.2007.12455.x,
  3. ^ a b c d e f Peter Jutzi, Ulrich Schubert, (2003), Silicon chemistry: from the atom to extended systems, Wiley-VCH ISBN 3527306471
  4. ^ Charles A. Schacht Refractories handbook (2004), CRC Press, ISBN 0824756541
  5. ^ Some comments on so-called silicon monoxide, Friede B., Jansen M., Journal of Non-Crystalline solids , 204, 2, (1996), 202-203, doi:10.1016/S0022-3093(96)00555-8
  6. ^ TEM investigation on the structure of amorphous silicon monoxide, Schulmeister K. and Mader W., Journal of Non-Crystalline Solids, 320, 1-3, (2003), 143-150, doi:10.1016/S0022-3093(03)00029-2