Which of the following complexes formed by Cu²⁺ ions are most stable?

(i) Cu²⁺ + 4NH₃⇌[Cu(NH₃)₄]²⁺,log⁡K=11.6

(ii) Cu²⁺ + 4CN−⇌[Cu(CN)₄]²⁻,log⁡K=27.3

(iii) Cu²⁺ + 2en⇌[Cu(en)₂]²⁺,log⁡K=15.4

(iv) Cu²⁺ + 4H₂O⇌[Cu(H₂O)4]²⁺,log⁡K=8.9

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