Siloxide
# Siloxide

Siloxides are chemical compounds with the formula $R_3SiOM,$ 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:

    $R_3SiOSiR_3$ + 2 NaOH → 2 $R_3SiONa$ + $H_2O$

Cleavage of cyclic siloxanes affords siloxides:

    $(Me_2SiO)_3$ + MeLi → $Me_3SiOSiMe_2OSiMe_2OLi$

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 $tert-butyl_3SiO^−,$ sometimes called silox.

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

