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The answer is (a) 3

(iii) [Fe(C₂O₄)₃]^3–

There are two principal types of isomerisms in coordination compounds as follows : 

(A) Stereoisomerism 

(B) Structural isomerism (OR Constitutional isomerism)

(A) Stereoisomerism is further classified as :

• Geometrical isomerism 
• Optical isomerism

(B) Structural isomerism is further classified as :

• Ionisation isomerism 
• Linkage isomerism 
• Coordination isomerism 
• Solvate (or hydrate) isomerism 

(i), (iii)

(i) [MnCl₆]^3–

^{(iii) [CoF₆]3–}

(a) Coordination number of Co in [CoCl₂(en)₂]⁺ = 6 

(b) Coordination number of Ir in [Ir(C₂O₄)₂ Cl₂]³⁺ = 6 

(c) Coordination number of Pt in [Pt(NO₂)₂ (NH₃)₂] = 4

1. Raju’s statement is correct. Coordination compounds are usually coloured.

2. The colour of coordination compounds is due to d-d transition.

1. Potassiumhexacyanoferrate (III)

2. Pentaamminecarbanatocobalt (III) chloride

(a). On the basis of application of coordination compounds : 

• In biological system – Haemoglobin, Vitamin B₁₂, Chlorophyll.
• Estimation of hardness of water – EDTA.
• Extraction of metals – Ni(CO)4
• n medicine – D-penicillamine, cis-platin

(b). The coordination compounds are : 

1. K₃[Fe(C₂O₄)₃] – Potassiumtrioxalatoferrate(III)

2. [Cr(CN)₃]³⁺ – Trisethylenediaminechromium(III) ion

3. [CoSO₄(NH₃)₄]NO₃ – Tetraamminesulphato- cobalt(III) nitrate

4. [CO(NO₂)₃ (NH₃)₃] – Triamminetrinitrito-N-cobalt(III)

(c) 0

The charge of Ni in [Ni(CO)₄] is 0. 

The principle of additive nomenclature is followed while naming the coordination compounds. 

The following rules are used

(i) The cation is named first in both positively and negatively charged coordination entities. 

(ii) The ligands are named in an alphabetical order before the name of the central atom/ion. 

(iii) The name of the anionic ligands end in –o, those of neutral and cationic ligands are the same except aqua for H₂O, ammine for NH₃, carbonyl for CO and nitrosyl for NO. these are placed within enclosing marks . 

(iv) When the prefixes mono, di, tri, etc., are used to indicate the number of the individual ligands in the coordination entity. When the names of the ligands include a numerical prefix, then the terms, bis, tris , tetrakis are used, the ligand to which they refer being placed in parenthesis. 

(v) Oxidation state of the metal in cation, anion, or neutral coordination entity is indicated by roman numeral in parenthesis. 

(vi) If the complex ion is a cation , the metal is same as the element. 

(vii) The neutral complex molecule is named similar to that of the complex cation. 

(i) Tetraammine aqua chloridocobalt(III)chloride. 

(ii) Dichlorido bis (ethane-1,2-diamine)chromium(III) Chloride

Following rules are followed for naming coordination compounds recommended by IUPAC :

1. In case of a complexion or a neutral molecule, name the ligand first and then the metal.

2. The names of anionic ligands are obtained by changing the ending -ide to -o and -ate to -ato.

3. The name of a complex is one single word. There must not be any space between different ligand names as well as between ligand name and the name of the metal.

4. After the name of the metal, write its oxidation state in Roman number which appears in parentheses without any space between metal name and parentheses.

5. If complex has more than one ligand of the same type, the number is indicated with prefixes, di-, tri-, tetra-, penta-, hexa- and so on. 

6. For the complex having more than one type of ligands, they are written in an alphabetical order. Suppose two ligands with prefixes are tetraaqua and dichloro. While naming in alphabetical order, tetraaqua is written first and then dichloro. 

7. If the ligand itself contains numerical prefix in its name, then display number by prefixes bis for 2, tris for 3, tetrakis for 4 and so forth. Put the ligand name in parentheses. 

For example, 

(ethylenediamine)3 or (en)3 would appear as tris (ethylenediamine) or tris(ethane-l, 2-diamine). 

8. The metal in cationic or neutral complex is specified by its usual name while in the anionic complex the name of metal ends with 'ate'.

Since in these two given complexes, there is an exchange of ligands between cationic and anionic constituents, they exhibit coordination isomerism.

(ii) Cu²⁺ + 4CN^– → [Cu(CN)₄]^2–, logK = 27.3

Option : (a) 0

Option : (b) 2, 0

(iv) Assertion is false, reason is true.

• In a coordination compound the coordination number is the number of donor atoms of ligands directly attached to metal atom or ion.
• In a solid state, the number of closest constituent atoms or ions in contact with a particular atom in the crystal lattice is called coordination number.
• In a coordination compound, coordination number depends upon nature of metal atom or ion, and its electronic configuration.
• In a solid state, the coordination number depends upon the crystalline structure of the unit cell.

(i) Role of coordination compounds in biological systems:
We know that photosynthesis is possible by the presence of the chlorophyll pigment. This pigment is a coordination compound of magnesium. In the human biological system, several coordination compounds play important roles. For example the oxygen – carrier of blood, i.e haemoglobin is a coordination compound of iron.

(ii) Role of coordination compounds in Medicinal chemistry: Certain coordination compounds of platinum (for example cis-platin) are used for inhibiting the growth of tumors.

(iii) Role of coordination compounds in analytical chemistry: During salt analysis, a number of basic radicals are detected with the help of the colour changes they exhibit with different reagents. These colour changes are a result of the coordination compounds or complexes that the basic radicals form with different ligands.

(iv) Role of coordination compounds in interaction or metallurgy of metals: The process of extraction of some of the metals from their ores involves the formation of complexes. For example in aqueous solution, gold combines with cyanide ions to form [Au(CN)₂]. From this solution, gold is later extracted by the addition of Zn metal.

The complex ion has formula, [Co(NH₃)₄CI₂]⁺. 

The charge number is + 1.

Option : (b) 2

(iii) The given complex can be written as

[CO(NH₃)₆]Cl₂ Thus, [CO (NH₃)₆]⁺ along with two Cl^- ions are produced.

Option : (b) [Fe(H₂O)₆]²⁺

(i) n = 3

µ = \(\sqrt{n(n+2)}\)

= \(\sqrt{3(3+2)}\)

= \(\sqrt{15}\)

≈ 4BM

(ii) n = 4

µ = \(\sqrt{4(4+2)}\)

= \(\sqrt{24}\)

≈ 5 BM

(iii) n = 0
μ = 0
Hence [FeCH₂O)₆]²⁺ has the highest magnetic moment value.

(i) A - [Co(NH₃)₅SO₄]Cl

B - [Co(NH₃)₅Cl]SO₄

(ii) Ionisation isomerism

(iii) (A), Pentaamminesulphatocobalt (III) chloride

(B), Pentaamminechlorocobalt (III) sulphate.

When white light falls on the complex, some part of it is absorbed. Higher the crystal field splitting, lower will be the wavelength absorbed by the complex. The observed colour of complex is the colour generated from the wavelength left over.

(iii) 8,000 cm^–1