Three moles of \( \mathrm{AgCl} \) get precipitated when one mole of an octahedral co-ordination compound with empirical formula \( \mathrm{CrCl_3 \cdot 3NH_3 \cdot 3H_2O} \) reacts with excess of silver nitrate. The number of chloride ions satisfying the secondary valency of the metal ion is __________.