The intermediate compound ‘X’ in the following chemical reaction is :

The given chemical reaction is the Etard reaction, which is used for the selective oxidation of the methyl group in toluene to an aldehyde group to form benzaldehyde.

Step-by-Step Reaction Mechanism:
1. Formation of the Intermediate:
When toluene ($C_6{H}_{5}C{H}_3$) is treated with chromyl chloride ($Cr{O}_{2}C{l}_2$) in a non-polar solvent like carbon disulfide ($C{S}_2$), the chromyl chloride oxidizes the methyl group of toluene. Two molecules of chromyl chloride add to the methyl carbon, forming a brown-colored chromium complex intermediate 'X'.
The chemical formula of this intermediate complex is:
$C_6{H}_{5}CH(OCrOHC{l}_2{)}_2$

2. Hydrolysis to Benzaldehyde:
Upon subsequent acidic hydrolysis using hydronium ions ($H_3{O}^{+}$), this chromium complex decomposed to yield benzaldehyde ($C_6{H}_{5}CHO$).

Therefore, the intermediate compound 'X' is the chromium complex represented as $C_6{H}_{5}CH(OCrOHC{l}_2{)}_2$.