Number of stereoisomers possible for the complexes, [CrCl3(py)3] and [CrCl3(ox)2]3- are respectively (py = pyridine, ox…

🧠 Compute Stereoisomer Counts

Stereoisomer = geometric + optical (enantiomers count separately).

🗺️ (a) $[\mathrm{CrCl_3(py)_3}]$ — Type $MA_3 B_3$

Octahedral $MA_3 B_3$ → fac (3 like ligands on one face) and mer (3 like ligands on a meridian).

Both fac and mer are achiral (each has a mirror plane).

Stereoisomer count = 2.

🗺️ (b) $[\mathrm{CrCl_2(ox)_2}]^{3-}$ — Type $[M(AA)_2 B_2]$

(Note: the formula in the question is keyed as 3 Cl + 2 ox, which exceeds 6 donors; the chemistry-consistent reading is $[\mathrm{CrCl_2(ox)_2}]^{3-}$, type $[M(AA)_2 B_2]$.)

• trans isomer: Cl axial-axial (180°), achiral. Count = 1.
• cis isomer: Cl cis (90°), chiral → 2 enantiomers (Δ, Λ). Count = 2.

Stereoisomer count = $1 + 2 =$ 3.

🗺️ Final

(a) 2 ; (b) 3.

⚡ Stereoisomer Counting Summary

| Type | Geometric | Optical | Total stereoisomers | |---|---|---|---| | $MA_3 B_3$ (oct) | fac, mer | none | 2 | | $M(AA)_2 X_2$ (oct) | cis (chiral), trans | cis Δ/Λ | 3 | | $M(AA)_3$ | one form | Δ/Λ | 2 |

⚠️ cis-$M(AA)_2 X_2$ Counted as Δ + Λ

cis form is chiral, contributing 2 enantiomers. trans is achiral, contributing 1. Total = 3.

$\boxed{\text{Answer: (3) 2 and 3}}$