The number of possible optical isomers for the complexes ${\mathrm{M}\mathrm{A}}_2{\mathrm{B}}_2$ with ${\mathrm{s}\mathrm{p}}^3$ and $\mathrm{d}\mathrm{s}\mathrm{p}{\mathrm{p}}^2$  hybridized metal atom, respectively is:

[Note: A and B are unidentate neutral and unidentate monoanionnic ligands, respectively]

CoCl₃.NH₃ + AgNO₃ $\stackrel{}{\to }AgC\mathcal{l}\downarrow \left(2mol\right)$  

$\left[Co{\left(N{H}_3\right)}_{5}C\mathcal{l}\right]C{\mathcal{l}}_2+AgN{O}_3\stackrel{}{\to }AgC\mathcal{l}\downarrow \left(2mol\right)$  

x = 5

In H₂O (polar solvent) dibromophenol derivative and in CS₂ (non-polar solvent moneobromo phenol derivate is obtained.

3d => 4d => 5d CFSE increases for the same ligands.

Factual
⇒ leaching methods is used for those metal in which metal is more soluble than impurities and these are Al, Au, Ag, low grade Cu

σ bonded organometallic compound ⇒ M – C
σ-bond
and in π – bonded organo metallic compound
M – C
π bond
In ferrocene, there is π-bond