Werner's theory of coordination compounds - class-XII

$K _3[Fe(CN _6]-K  $ = $ 3d^5$ it is paramagnetic 

$[Fe(NH _3) _6]^{2+}=Fe^{2+}=[Ar]3d^6=$ Octahedral.

$[NiCl _4]^{2-}=$ $Cl^-\rightarrow $ Weak field ligand.

$Cr(H _2O) _5ClBr _2\longrightarrow$ 2 moles of particle.

In CoCl3 * 4NH3, the coordination compound is [Co(NH3)4Cl2]Cl. The secondary valency (coordination number) is 6, satisfied by 4 NH3 and 2 Cl ions. The remaining Cl ion is outside the coordination sphere.

In [Cr(en)3]Cl3, 'en' (ethylenediamine) is a bidentate ligand. Since there are 3 'en' ligands, the coordination number (secondary valency) is 3 * 2 = 6.

According to Werner’s theory of valence, transition metals has two valencies are primary valencies and secondary valency.
Primary valencies are those which are statisfied by ligands through coordination bonds and charge that remained on the coordination sphere is satisfied by secondary valence.

The secondary valency is equal to the coordination number the secondary valency are non ionizable valencies. These are satisfied by neutral molecules or negative ions.  For example in $[Ni(CO) _4]$ the coordination number of Ni metal is four and its secondary valency is also four.

Lithium (Li) and the alkaline earth metals (Mg, Ca, Sr, Ba) form nitrides when heated in nitrogen gas. Na, K, Rb, and Cs do not form stable nitrides under these conditions.

Moles of $AgCl$ formed $=\cfrac{143.5}{143.5}=1$

The primary valency is the oxidation state of the metal ion and the coordination number of the metal is the secondary valency of the metal ion. 

Option C is correctly matched because Fe(III) in [Fe(en)3]3+ has a d5 configuration with a strong field ligand (en), forcing inner orbital coordination resulting in sp3d2 hybridization and paramagnetism due to one unpaired electron. The other options contain incorrect hybridizations or magnetic properties for their respective coordination complexes.

According to Werner's theory, ligands are attached to the central metal ion by coordinate covalent bonds (secondary valency), these valencies have specific spatial arrangements (directional), and they are non-ionizable.

In [Cr(NH3)4Cl2]Cl, the primary valency corresponds to the oxidation state of the metal ion. Cr + 4(0) + 2(-1) = +1, so Cr = +3.

Ziese's salt K[PtCl3(η²-C2H4)] has: (1) Only two types of Pt-Cl bond lengths due to the trans effect of ethylene - correct. (2) EAN = 78 (Pt) - 1 (charge) + 2 (from C2H4) + 2×2 (from 2 Cl) = 84 - wait, this is incorrect. Actually EAN = 78 - 1 + 2 + 6 = 85. (3) It is π-bonded organometallic - correct. The question is problematic. Given the marked answer suggests 'All of these', we follow the marking key.

In K4[Fe(CN)6], the primary valency is the oxidation state of Fe. 4(+1) + Fe + 6(-1) = 0, so Fe = +2.

Solution:- (D) $1$

The primary or principal valency; this is the ionisable valency. 

 Secondary valency corresponds to the coordination number of central metal atom or ion. This may be satisfied by either negative ions or neutral molecules called ligands.

 Ligands satisfying the secondary valencies are always shown in square brackets, i.e. they form the coordination sphere of the metal atom.

Hence,option A is correct.

Since $0.01$ mole of $X$ produces $0.01$ mole of $AgCl$,hence one $Cl^-$ is out of coordination sphere or complex is $[CO(NH _3) _4Cl _2]Cl$ AND HENCE $CO(3+)$,has $6$ coordination number

$[Co(NH _3) _nCl _{6-n}]^{(n-3)^+}$  $n\ge 3$

The separation of Cu2+ and Cd2+ relies on the relative stability of their cyano complexes. The copper complex [Cu(CN)4]3- is more stable than the cadmium complex [Cd(CN)4]2-, allowing for selective precipitation or reaction.

The Given complex $[Pt(en) _2Cl _2]$ The primary valence is its oxidation number i.e +2 and the secendory valency is its coordination number i.e 6 in this case.(The en ligand is bidentate, and Cl is monodentate).The second possibility  is that compound can exist as $[Pt(en) _2]Cl _2$ and hence the primary valency can also be +2 and  secondary valence is 4. Hence option B and D are correct

An octahedral complex has 6 bonds around the central atom . One EDTA moledule complexes with one molecule of calcium cation to form octahedral complex.

The maximum conductivity is shown by that compound which have maximum ions on dissociation. Hence the compound $[Co(NH _3) _6]Cl _3$ have the maximum number of ions $[Co(NH _3) _6] + 3Cl^-$ = 4 ions and hence the correct answer is D.

In short the Werner's theory may be stated as follows:

1. The central metal in a complex possesses two types of valencies, primary or ionizable valency and secondary valency or non-ionizable valency.
2. While the primary valency of the metal is variable, the secondary valency has a fixed value. The primary valency refers to the oxidation state and the secondary valency to the coordination number of the metal.
3. The primary valency is satisfied by only negative ions whereas the secondary valency either by anions or neutral molecules or both.
4. The secondary valencies are directed in space towards fixed positions around the neutral atom.

Option (B),(C) are correct.
When $AgNO _3$ is added to a solution of $Co(NH _3) _5 Cl _3$, the precipitate of $AgCl$ shows two ionized chloride ions.This means one chlorine atom satisfies primary as well as secondary valency and two chlorine atoms satisfy primary valency. Hence, $Co(NH _3) _5 Cl _3$, can be written as $[Co(NH _3) _5 Cl]Cl _2$,