Siloxides are chemical compounds with the formula R3SiOM, where R is usually an organic group and M is usually a metal cation. Also called silanolates, they are derived by deprotonation of silanols. They also arise by the degradation of siloxanes by base:[1]

R3SiOSiR3 + 2 NaOH → 2 R3SiONa + H2O

Cleavage of cyclic siloxanes affords siloxides:

(Me2SiO)3 + MeLi → Me3SiOSiMe2OSiMe2OLi

These anions function as ligands for metal ions, forming complexes similar to metal alkoxides. Sodium trimethylsiloxide is useful for generating metal complexes by salt metathesis reactions. A very bulky siloxide is tert-butyl3SiO−, sometimes called silox.

Siloxides are weaker net donors than alkoxides because pπ-d donation has to compete with backbonding from the oxygen atom into the low-lying Si-C σ* orbitals.[1]

References

  1. 1 2 Krempner, Clemens (2011). "Role of Siloxides in Transition Metal Chemistry and Homogeneous Catalysis". Eur. J. Inorg. Chem. 2011 (11): 1689. doi:10.1002/ejic.201100044.
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