Sulphur containing the compound ‘P’ on boiling with sulfur gives an addition compound ‘Q’. ‘Q’ in reaction with ${\mathrm{PbCl}}_2$ Forms a lead compound. This lead compound on further boiling gives one more lead compound 'R' . Same compound ‘Q’ on reaction with cupric salt$\left({\mathrm{CuCl}}_2\right)$  Forms at the end a complex salt ‘S’, then