The given reaction is the Etard reaction. In this reaction, chromyl chloride ($CrO_2Cl_2$) is used as an oxidizing agent in a non-polar solvent like $CS_2$. It oxidizes the methyl group of toluene to form a brown-coloured chromium complex as an intermediate. This intermediate complex, upon subsequent acid hydrolysis ($H_3O^+$), yields benzaldehyde. The structure of the intermediate chromium complex 'X' is $C_6H_5-CH(OCrOHCl_2)_2$.