The product(s) when dichlorine hexoxide reacts with NaOH is(are):
NaClO3
In the gaseous state, the formula Cl2O6 is accurate but in the liquid (red) and solid states, the compound exists as chloryl chlorate - [ClO+2][ClO−4]. strangely, it is not a dimer of the other chlorine oxide - ClO3. At room temperature, it is a dark red fuming liquid that crystallizes into a red ionic solid.
Cl2O6+2NaOH⟶NaClO4+NaClO3+H2O