Previous Years' CBSE Board Questions

9.1 Werner's Theory of (b) Both Assertion (A) and Reason (R) are
correct statements, but Reason (R) 0s not
Coordination Compounds the correct explanation of the Assertion
VSA (1 mark) (A).
One mole of CrCl,6H,0 compound reacts (c) Assertion (A) is correct, but Reason (R)
is incorrect statement.
with excess AgNO, solution to yield two (d) Assertion (A) is incorrect, but Reason
moles of AgCl The structural formula of (R) is correct statement. (2020)
the compound is
(a) [Cr(H,0),CIJ CIL,- H,0 7. Write the coordination number and
(b) [Cr(H,0),Cl,]· 3H,0 oxidation state of platinum in the complex
(c) [Cr(H0),C,|CI-2H,0 (P(en),Cl,]. (2018)
(d) [Cr(H,0),Cl,) (2020) 8. Which of the following is more stable
complex and why?
2. When a coordination compound CrCl-6H,0
is mixed with AgNO, 2 moles of AgCl are [Co(NH,)Al" and [Co(en),|]" (Delhi 2014)
precipitated per mole of the compound. 9. What do you understand by 'denticity of a
Write structural formula of the complex. ligand'? (Foreign 2011)
(AI 2019, 1/2, Delli 2016)
SA (2 marks)
3. What is the difference between a complex
and a double salt? (AI 2019) 10. Explain the following terms giving asuitable
4. When acoordination compound CoCl,-6NH, example in each case :
is mixed with AgNO, 3moles of AgCl are () Ambidenate ligand
precipitated per mole of the compound. (ii) Denticity of a ligand (2/3, Al 2011)
Write structural formula of the complex. 9.3 Nomenclature of Coordination
(/2, Al 2016)
Compounds
9.2 Definition of Some Important VSA (1 mark)
Terms Pertaining to
11. Write the formula of the following
Coordination Compounds coordination compound :
VSA (1 mark) Iron (III) hexacyanidoferrate(I1) (1/3, 2018)
5. The coordination number of 'C¡ in the 12. Write the IUPAC name of the following
complex [Co(en),]+ is complex : [Cr(NH),C,]. (1/3, Delhi 2017)
(a) 3 (b) 6 13. Write the IUPAC name of the following
(c) 4 (d) 5 (2020) complex: (Co(NH),(CO,)]CI.
(1/3, Delli 2017)
6 Assertion (A) : [Pr(en),Cl,J2* complex is less
stable than [P(NH),Cl,]²* complex. 14. Whena coordination compound CrCl,-6H,0
Reason (R) : (Pt(en),CI,j2* complex shows is mixed with AgNO,, 2 moles of AgCl are
chelate effect. precipitated per mole of the compound.
(a) Both Assertion (A) and Reason (R) are Write IUPAC name of the complex.
correct statements, and Reason (R) is (1/2, Delhi 2016)
the correct explanation of the Assertion 15. Write the IUPAC name of the complex
(A). (Cr(NH),Cl,]CI. (1/3, AI 2014)
16. Write down the formula of : 27. Using IUPAC norms write the formulae for
Tetrammineaquachloridocobalt(lI)chloride. the following coordination compounds:
(AI 2012C) (i) Hexaamminecobalt(III) chloride
17. Name the following coordination compound: (ii) Potassium tetrachloridonickelate(II)
K,[CrFl. (Foreign 2011) (AI2015)
18. Write the IUPAC name of 28. (i) Write down the IUPAC name of the
[PrCl(NH,CH) (NH),JCI. (Dellhi 201IC) following complex : (Cr (en),]Cl,.
19. Write the IUPAC name of [P(NH,),CI,JCI,.
(ii) Write the formula for the followingcomplex :
Potassium trioxalatochromate (III).
(AI 2011C) (Foreign 2015)
20. Write the IUPAC name of
29. Namethe following coordination compounds
[Cr(NH)J[Co(CN),J. (AI 2011C) and draw their structures:
SA (2 marks) (0) (CoCl,(en),]CI
(i) [P(NH),CI(NO,)1
21. Give the formulae of the following (At. No. Co = 27, Pt = 78)
compounds: (Foreign 2011)
(a) Potassium tetrahydroxidozincate(l) LAT (3 marks)
(b) Hexaammineplatinum(IV) chloride
(2020) 30. Write the IUPAC name of the following:
22. Using IUPAC norms write the formulae for (0) (Co(NH,),]C, (G) [NiCI,J2
(ii) K,[Fe(CN)] (AI 2015C)
the following :
31. Write down the IUPAC name for each of the
(i) Pentaamminenitrito-0-cobalt(III)
chloride following complexes:
(ii) Potassium tetracyanidonickelate(|I) (1) [Co(NH,),CIJCI, (ii) K,[Fe(CN)A]
(Delli 2019) (iiü) (NiCl]2 (Dellhi 2014C)
32. Write the IUPAC name and draw the
23. Using IUPAC norms write the formulae for
the following : structure of each of the following complex
entities:
(a) Sodium dicyanidoaurate(1)
(b) Tetraamminechloridonitrito-N-platinum(1V) (i) (i) (Cr(CO).]
sulphate (AI 2017)
24. Using IUPAC norms write the formulae for (ii) [PICI,(C,H)I
the following: (At. nos. Cr = 25, Co = 27, Pt =78)
(a) Tris(ethane-1,2,diamine)chromium(I) (AI 2014C)
chloride
33. Write the IUPACnames of the following
(b) Potassium tetrahydroxozincate(1) coordination compounds :
(AI 2017)
(i) (Cr(NH),CIJ
25. Using IUPAC norms write the formulae for (Gi) K,[Fe(CN)]
the following: (ii) [CoBr,(em),]', (en = ethylenediamine)
(a) Potassium trioxalatoaluminate(III) (Delhi 2013)
(b) Dichloridobis(ethane-1,2-diamine)
cobalt(II) (AI 2017) 9.4 Isomerism in Coordination
26. (i) Write down the IUPAC name of the Compounds
following complex : VSA (1 mark)
[CrNH),Cl(en)]Cl(en=ethylencdiamine)
(ii) Write the formula for the following complex: 34. Assertion (A) : Linkage isomerism arises
Pentaamminenitrito-O-cobalt (II). in coordination compounds because of
(Dellhi 2015) ambidentate ligand.
 Reason (R) : Ambidentate ligand like NO, 46. What type of isomerism is exhibited by the
has two different donor atoms i.e., N and O. following complex :
(a) Both Assertion (A) and Reason (R) are [Co(NH,),So,]CI (Foreign 2014)
correct statements, and Reason (R) is 47. What type of isomerism is exhibited by the
the correct explanation of the Assertion complex (Co(NH,),NO,]P"? (Foreign 2014)
(A). 48. Indicate the types of isomerism exhibited
(b) Both Assertion (A) and Reason (R) are by the complex (Co(NH,),(NO,)](NO,),.
correct statements, but Reason (R) is not (At no. Co = 27) (AI 2012C)
the correct explanation of the Assertion 49. Give IUPAC name of ionisation isomer of
(A). [Ni(NH,),NO,]CI. (AI2012C)
(c) Assertion (A)is correct, but Reason (R)
is incorrect statement. SA (2 marks)
(d) Assertion (A) is incorrect, but Reason 50. Write IUPAC name of the complex
(R) is correct statement. (2020) [Cr(NH),CI,]". Draw structures of
35. What type of isomerism is shown by the geometrical isomers for this complex.
complex (Co(en), CI,]*? Name the structure (Delli 2019)
of an isomer of this complex which is 51. Draw the structure of isomers, if any and
optically active. (1/2, 2020) write the name of the following complexes :
36. What type of isomerism is exhibited by the (i) (Cr(NH),CI,J"
complex [Co(NH),CI]SO,? (1/3, 2018) (i) [Cofen),] (Foreign 2011)
37. What type of isomerism is shown by the LAI (3 marks)
complex [Co(NH)AJ[Cr(CN),J? 52. Indicate the types of isomerism exhibited by
(1/3, Delli 2017, Foreign 2014) the following complexes:
38. What type of isomerism is shown by the (i) [Co(NH),(NO,)|²*
complex [Co(en),JCI,? (1/3, Delli 2017) (ii) (Co(en),JCl, (en = ethylene diamine)
39, What type of isomerism is shown by the (ii) [PI(NH),C,| (Dellhi 2015C)
complex (Co(NH),(SCN)J*? 53. Write the IUPAC name of the complex
(1/3, AI 2017) [Cr(NH,),CI,]". What type of isomerism
does it exhibit? (Delhi 2014)
40. Draw one of the geometrical isomers of the
54. Draw the structures of optical isomers of
complex (Pr(en),Cl,]²+ which is optically each of the following complex ions :
active. (1/3, Dellhi 2016)
[Cr(C,O), (PIC,(en), 2*, [Cr(NH),C;(en)]'
41. Draw one of the geometrical isonmers of the (Dellhi 2014C)
complex [Pr(en),Cl,|2* which is optically
inactive. (AI 2016) 55. Write the types of isomerism exhibited by
the following complexes :
42. Draw the geometrical isomers of complex (i) [Co(NH),CIJSO,
[P(NH),C,). (1/3, Delli 2015) (i) (Cofen),]+*
43. Write down the IUPAC name of the complex (ii) (Co(NH,)J [Cr(CN)J (Dellhi 2013)
[Pt(en),Cl,2*. What type of isomerism is 56. Name the following coordination entities and
shown by this complex? (AI 2015)
draw the structures of their stereoisomers:
44. Draw the geometrical isomers of complex (i) [Cofen),Cl,]* (en = ethane-1,2-diamine)
[P(en),Cl,|2*. (1/3, Foreign 2015) (ii) (Cr(C0,),J
45. What type of isomerism is exhibited by (ii) [Co(NH),CIJ
the complex [Co(en),]*? (en = ethane-1,2 (Atomic numbers Cr = 24, Co = 27)
diamine) (1/3, AI 2014) (AI 2012)
57. Write the structures and names of all the 67. (a) Why is [NiCI,]' paramagnetic while
stereoisomers of the following compounds : [Ni(CN),|2- is diamagnetic?
() (Colen), |Cl, (i) [P(NH),CI,) (Atomic number of Ni = 28)
(ii) [Fe(NH),CH]CI (AI 2011)
(b) Why are low spin tetrahedral complexes
rarely observed? (2/3, AI 2017)
9.5 Bonding in Coordination
68. For the complex [Fe(CN),, write the
Compounds hybridization type, magnetic character and
VSA (1 mark) spin nature of the complex.
(At. number : Fe = 26). (2/3, Dellhi 2016)
58. The crystal field splitting energy for
octahedral (A) and tetrahedral (4,) 69. For the complex (Fe(H,0),]", write the
complexes is related as hybridization, magnetic character and spin
2 of the complex. (At. number Fe = 26)
(a) A, A (2/3,AI 2016)
4
(c) A, =A, (d) A, = 2 A, (2020) 70. () On the basis of crystal field theory, write
the electronic configuration of d' ion
59. Write the IUPAC name and hybridisation if A, <P.
of the complex (CoF] (Given : Atomic (i) Write the hybridization and magnetic
number of Co = 27) (1/2, 2020)
behaviour of the complex (Ni(CO)].
60. Write the hybridisation and number of (At. no, of Ni -28) (2/3, Delli 2015)
unpaired electrons in the complex (CoF,). 71. Write the hybridization and shape of the
(Atomic no. of Co = 27) (1/3, 2018)
61. Why a solution of [Ni(H,0).J²* is green following complexes :
while a solution of [Ni(CN),J2- is colourless? (i) [CoF,l- (i) (Ni(CN),]2
(At. no. of Ni = 28) (1/3, Dellhi 2017) (Atomic number : Co = 27, Ni = 28)
(AI 2015)
62. Write the hybridisation and magnetic
character of [Co(C,0,)J. 72. Write the state of hybridization, shape and
(At. no. of Co = 27) (1/3, Dellhi 2017) IUPAC name of the complex (CoF,].
63. Why is [NiCI,] paramagnetic but (Ni(CO)) (Atomic no. of Co = 27) (Foreign 2014)
is diamagnetic? (At. no. : Cr = 24, Co = 27, 73. Write the state of hybridization, shape and
Ni= 28) (1/3, AI 2014)
IUPAC name of the complex [Ni(CN),12-.
64. Explain the following term giving a suitable (Atomic no. of Ni =28) (Foreign 2014)
example:
74. Write the state of hybridization, shape and
Crystal field splitting in an octahedral field. IUPAC name of the complex [Co(NH)|.
(1/3, AI 2011)
SA (2 marks)
(Atomic no. of Co = 27) (Foreign 2014)

65. Write IUPAC name and hybridization of the

75. Give the formula of each of the following
coordination entities:
following complexes : (i) Co ion is bound to one Cl, one NH,
(0) (Ni(CO)] (ii) (CoF]
(Atomic number Ni = 28, Co = 27) (2020) molecule and two bidentate ethylene
diamine (en) molecules.
66. Out of (CoF] and (Co(C,0),], which (ii) N²' ion is bound to two water molecules
one complex is and two oxalate ions.
() diamagnetic (ii) more stable
(i) outer orbital complex and Write the name and magnetic behaviour of
(iv) low spin complex ? each of the above coordination entities.
(Atomic no, of Co = 27) (Dellhi 2019) (At. nos. Co = 27, Ni = 28) (2/3, Dellhi 2012)
76. State a reason for each of the following 85. Name the following coordination entities
situations: and describe their structures.
(i) Co is easily oxidised to Co in () [Fe(CN)J
presence of a strong ligand. (ii) [Cr(NH),CI,]*
(i) The molecular shape of Ni(CO), is not (iiü) [Ni(CN),J² (AI 2012)
the same as that of [Ni(CN)J. 86. Write the name, stereochemistry and
(2/3, Dellhi 2012) magnetic behaviour of the following:
77. Using valence bond theory, explain the (At. nos. Mn = 25, Co = 27, Ni = 28)
geometry and magnetic behaviour of (i) K[Mn(CN)]
[Co(NH).]". (i) [Co(NH),CI]Cl,
(At. no. of Co = 27) (2/3, Delhi 2012C) (ii) K,[Ni(CN)J (Delli 201)
78. Using valence bond theory of complexes, 87. For the complex [e(en),CI,]CI, identify the
explain the geometry and magnetic nature of following :
[Ni(CN),J. (At. no. of Ni=28) (i) Oxidation number of iron
(2/3, Delhi 2012C) (i) Hybrid orbitals and shape of the
complex
79. [Fe(H,0)J" is strongly paramagnetic
whereas (Fe(CN),]- is weakly paramagnetic. (ii) Magnetic behaviour of the complex
Explain (At. no. Fe = 26] (Dellhi 2012C) (iv) Number of its geometrical isomers
(v) Whether there may be optical isomer
80. Give the name, the stereochemistry and also.
the magnetic behaviour of the following (vi) Name of the comple. (Delli 201l)
complexes: 88. Write the state of hybridization, the shape
(i) [Co(NH),CIJCI,
(i) K,[Ni(CN),J (Foreign 2011) and the magnetic behaviour of the following
complex entities :
LAI (3 marks) (i) [Cr(NH),CHJCI
81. Write the hybridisation and magnetic (ii) [Cofen),]Cl,
character of thefollowing complexes: (ii) K,[Ni(CN)| (AI 2011)
(i) [Fe(H,0),|2 (iü) (Ni(CN),J 9.6 Bonding in Metal Carbonyls
[Atomic number : Fe = 26, Ni = 28]
(AT 2019) VSA (1 mark)
82. For the complex (NiCL], write 89, Out of NH, and CO, which ligand forms a
(i) the IUPAC name more stable complex with a transition metal
(ii) the hybridization type and why? (1/3, AI 2015)
(ii) the shape of the complex. 90. State a reason for the following situation :
(Atomic no. of Ni = 28) (AI 2013) CO is a stronger complexing reagent than
83. What is meant by crystal field splitting NH,, (1/3, Dellhi 2012)
energy? On the basis of crystal field theory, 91. Why is CO a stronger ligand than CI?
write the electronic configuration of d' in (Foreign 2011)
terms of t, and e, in an octahedral field when
(i) A,>P 9.7 Importance and Applications
(ii) A,<P (AI 2013) of Coordination Compounds
84. Write the name, the structure and the
magnetic behaviour of each one of the VSA (1 mark)
following complexes : 92. Give two examples of coordination
(i) [P(NH),CI(NO,)| compounds used in industries.
(i) (Co(NH),CIHJCI (iiü) Ni(CO), (1/3, Delli 2012C)
(At. nos. Co = 27, Ni = 28, Pt =78) 93. Give names of two complexes which are used
(Dellhi 2012) in medicines. (1/3, Delhi 2012C)
 Detailed Solutions

1. For one mole of the compound, two moles 17. Potassium hexafluoridochromate(III).
of AgCl are precipitated which indicates two 18. Diamminechlorido(methylamine)platinum()
ionisable chloride ions in the complex. Hence, its chloride.
structural formula is [CrCl(H,0),JCI, H,0
2. Refer to answer 1. 19. Tetraamminedichloridoplatinum(IV) chloride.
3. Double salts dissociate into ions completely 20. Hexaanmminechromium(!I)
when dissolved in water. On the other hand, in hexacyanidocobaltate(II).
complexes, the complex ion does not dissociate. 21. (a) K[Zn(OH)4]
4. Structural formula : (Co(NH).JC, Potassium tetrahydroxidozincate(1I)
5. (b):Ethane-1, 2-diamine (en) is a bidendate (b) [P(NH)JCI,
ligand. Hexaammineplatinum(IV) chloride
6. (d):Formation of chelate rings increases the 22. (i) [Co(NH,),(ONO)JCI,
stability of the complex. (ii) K,[Ni(CN)J
7. Coordination number and oxidation state 23. (a) Na[Au(CN),]
of Pt in the complex (Pt(en),CI,] are 6 and +2 Sodium dicyanidoaurate()
because en is a bidentate and neutral ligand. (b) [Pt(NH,),(CI)(NO,)]SO,
8. [Co(en),]* is more stable complex than Tetraamminechloridonitrito-N-platinum(IV) sulphate
[Co(NH,)J due to chelate effect as it forms 24. (a) [Cr(en),]Cl,
rings. Tris(ethane-1,2-diamine)chromium(I) chloride
9. Denticity: The number of coordinatinggroups (b) K,[Zn(OH),|]
present in a ligand is called the denticity of ligand. Potassium tetrahydroxidozincate(lI)
For example, bidentate ligand ethane-1,2-diamine 25. (a) K,[AI(C,0),]
has two donor nitrogen atoms which can link to Potassium trioxalatoaluminate(II)
central metal atom.
(b) [CoClh(en),]*
H,Ñ-CH,-CH,-ÑH, Dichloridobis(ethane-1,2-diamine)cobalt(III) ion
Ethane-1, 2-diamine
10. (i) Ambidentate ligand : Aunidentate ligand
26. (i) Diamminedichlorido(ethane- 1,2
diamine) chromium(|l) chloride.
whichcancoordinateto centralmetalatomthrough
two different atoms is called ambidentate ligand. (ii) [Co(NH,),(ONO)|2
For example, NO, ion can coordinate either 27. (i) (Co(NH,)]CI, (ii) K,[NiCL]
through nitrogen or through oxygen to the 28. (i) Tris(ethylenediammine)chromium(III)
central metal atom/ion.
chloride
(ii) Refer to answer 9. (ii) K,[Cr(ox)l
11. Fe,[Fe(CN)Js
29. (i) Dichloridobis (ethane-1, 2-diamine)
12. IUPACname ofthe complex [Cr(NH),CI|] is cobalt(III) chloride.
triamminetrichloridochromium (llI).
CI
13. Pentaamminecarbonatocobalt(|) chloride
14. IUPAC name of the complex
(CrCl(H,0),|Cl,H,0 is :
pentaaquachloridochromium (III) chloride.
15. IUPAC name ofthecomplex [Cr(NH,),C,JCI enJ
is tetraamminedichloridochromium(I) chloride. Octahedral Octahedral
16. [Co(NH,),(H,0)(CI]CI, cis-(CoCl,(en),l' trans-(CoCl,(en),l"
(ii) Diamminechloridonitrito-N-platinum(I1) 38. The complex, [Co(en),]Cl, shows optical
H,N, CI isomerism.
39. The complex [Co(NH),(SCN)J² shows
linkage isomerism as SCN is an ambidentate ligand.
H,N NO,
30. (1) Hexaamminecobalt(III) chloride 40. cis-isomer of the complex [PI(en),CI,]P* is
(ii) Tetrachloridonickelate(lI) ion
optically active.
CI
(ii) Potassium hexacyanidoferrate(III)
31. () Pentaamminechloridocobalt(1) chloride en P1
(ii) Refer to answer 30(ii).
(ii) Refer to answer 30(i).
32. (i) Trioxalatocobaltate() 41. Trans-isomer is optically inactive due to the
presence of plane of symmetry.
C

(ii) Hexacarbonylchromium(0)
CO C1
oc co 42. Geometrical isomers
OC Co NH, NH,
(i) Trichloridoetheneplatinum(!II)
C SNH, H,N} CI
cis-Diamminedichlorido trans-Diamminedichlorido
Pt CI platinum() platinum(I1)
H 43. IUPAC name Dichloridobis(ethane-1,2
33. (1) Triamminetrichloridochromium(II) diamine)platinum(IV) ion. This complex shows
(ii) Refer to answser 30(ii) geometrical and optical isomerism.
(ii) Dibromidobis(ethane- 1,2-diamine) CI CI
cobalt(III) ion
34. (a)
35. [CoCl,(en),] : Dichloridobis(ethane-1,
en en en PU
2-diamine)cobalt(III) ion CI
This complex exhibit both optical and geometrical trans cis
isomerism and cis isomer is optically active.
cis-isomer is optically active.
C

trans-form en
cis-formnexists
exists in
two enantiomeric forms
(d and )
en
36. lonisation isomerism: [Co(NH,),CIJSO, and dextro
Mirror
e laevo
[Co(NH,),SO,JCI
37. Coordination isomerism 44. Refer to answver 43.
45. Optical isomerism : C Cl
73+

Len
dextro Mirror laevo
Tris(ethane-1, 2-diamine) Tristethane-1, 2-diamine)
cobalt(I1) ion cobalt() ion Mirror laevo
dextro
46. Refer to answer 36. [Cr(NH),C,(en)]*:
47. Linkage isomerism : (Co(NH),NO,]2* and
[Co(ONO)(NH),2* NH
H,N
48. (i) lonisation isomers :
[Co(NH),(NO,)|(NO), and
(Co(NH),(NO,)|(NO,)(NO,) H,N cNH,
Cl CI
(i) Linkage isomers : [Co(NH,),(NO)|(NO,), dextro
Mirror
laevo
and [Co(NH,),(ONO)]J(NO),
55. (i) Refer to answer 36.
49. lonisation isomer of [Ni(NH),NO,JCI
is [Ni(NH),CIJNO,. The IUPAC name of this (iü) Refer to answer 45.
complex is triamminechloridonickel(lI) nitrate. (iii) Refer to answer 37.
50. Tetraamminedichloridochromium(lII) ion 56. () Refer to answer 35.
Geometrical isomers of [Cr(NH),CI,]':
Cl
(ii) (Cr(C,0,),]: Trioxalatochromate(III) ion
Cl It will show optical isomerism.
H,N.
HNNH, Refer to answer 54.
(ii) (Co(NH),C,J: Triamminetrichloridocobalt(I)
It will exist in two geometrical isomeric forms:
NH,
"NH, H,NNH, NH,
cis-Tetraamminedichlorido
CI
trans-Tetraamminedichlorido NH, H,N!a
chromium(III) ion chromium(I1) ion Co
51. ()) Refer to answer 50. NH, aC
CI NH,
(ii) Refer to answer 45. Facial (fac) Meridional (mer)
52. (i) Refer to answer 47. 57. (i) tris(ethane- 1,2-diamine) cobalt(II)
(ii) Refer to answer 45.
chloride: Refer to answer 45.
(ii) Refer to answer 42.
(ii) Refer to answer 42.
53. Refer to answer 50. (i) (Fe(NH),CI,JCI
54. (Cr(C,0,)]-:
NH, CI
H,N. H,N.
Fe
H,N NH,
ox
)sl" Mirror [Cr(ox),j NH,
[C cis-tetraamminedichlorido trans-tetraamminedichlorido
laevo iron (II) iron (III)
[PrC,(en),]²: 58. (c)
59, The IUPAC name of [CoF.J is
hexafluoridocobaltate(II).
Oxidation state of Co ion in [CoF,] is +3. sp hybridisation
4d
(tetrahedral)
Co":([1|1T four electrons
donated by four
Co in (CoF]: CO ligands
(strong ligand)
3d 4s 4d
The complex has all paired electrons hence, it is
diamagnetic.
sp'd'hybridisation
six pairs of electrons
from six F ion
64. The splitting of the degenerate d-orbitals
(Weak ligands )
into three orbitals of lower energy, ty, set and two
orbitals ofhigher energy e, set due to the interaction
No, of unpaired electrons = 4 of ligand in an octahedral crystal field is known
60. Refer to answer 59. as crystal field splitting in an octahedral field.
61. [Ni(H,0)]²* is a high spin complex
(A, small) while [Ni(CN),J is a low spin square e
planar complex.
In [Ni(H,O),J complex, d-d transitions are Energy Average energy
of the d-orbitals
taking place on absorbing low energy radiation in a spherical d,, d, d,
d-orbitals in
(red component of spectrum) from visible region free metal ion
crystal field
showing green as the complementary colour. d-orbital splitting in an octahedral crystal field
In (Ni(CN),J² complex, d-d transitions do not
take place because there is no unpaired electron [Mn(H,0),.J* contains:Mn²t - 3d configuration
present hence, complex is colourles. C.N, = 6, octahedral structure, H,0 (weak field
ligand) hence A, < P
62. The complex [Co(C,0,),| has 'sp'.
hybridisation and it is diamagnetic in nature due 1111
to the absence of unpaired electrons. degenerate\111
d-orbitals in Weak octahedral
63. [NiC,] contains Ni' ion with 3 configuration. free metal ion.
ligand field
34d de 4p
Ni* Electrons enter into e, orbital before pairing. It has
Ground state five unpaired electrons.
CI is a weak field ligand. Hence, outer 4s and [Mn(CN),] contains : Mn ion-3d configuration,
4p-orbitals are used in hybridisation. C.N, = 6, octahedral geometry, CN (strong field
3d 49 4p ligand) hence, A, >P
(NiCI] 1L11txxx*x
with 4Cl igands
sp' hybridisation,
11111. A, > P
(tetrahedral)
4electron pairs donated Hence, pairing of electrons in t, orbitals takes
by 4Cl ligands place. It has only one unpaired electron.
(weak ligand)
It has two unpaired electrons hence, it is 65. (i) Name; Tetracarbonylnickel (0)
paramagnetic. For hybridisation; Refer to answer 63.
[Ni(CO),] contains Ni(0) - 3d4s configuration. (ii) Refer to answer 59.
Ni(0)
3d 4s 66. Formation of (CoF,] and [Co(C;0,),J
Ground state can be represented as :
3d
CO is a strong field ligand hence, 4s-electrons will (CoF,)-:14in
shift to 3d-orbital making 4s-orbital vacant.
 4s 1p 4d The complex ion has inner orbital octahedral
geometry (low spin) and is paramagnetic due to
six electron pairs
the presence of one unpaired electron.
donated by F ions 69. [Fe(H,0)]*:
(sp'd' hybridization) Fe atom (Z = 26)
[Co(C,0),]: 3/0 48
3d Ground state :[1|1|t||D
345 44

Fetion:
six electron pairs
donated by C,0, ions [Fe(H,0).JP":
3d5 4s 4d
(sp³ hybridization)
() (Co(CO),j is diamagnetic as allelectrons sp''hybridisation
are paired.
six pairs of electrons
(i) (Co(C,0,),] is more stable as C,0} is a from six H,0 ligands
(weak ligand)
chelating ligand and forms chelate rings.
The complex ion has outer orbital octahedral
(ii) [CoF, is outer orbital complex as it
geometry (high spin) and is paramagnetic due to
undergoes sp'd' hybridization using the outer the presence of five unpaired electrons.
4d-orbital.
70. () For d ion, if A, < P, the fourth electron
(iv) [Co(C,0)| is low spin complex due to enters one of the e, orbitals giving the configuration
absence of any unpaired electron.
67. (a) Due to the presence of weak field ligand, tig e Ligands for which A, < Pare known as
ie, CI in the complex (NiCL]2- two unpaired weak field ligands and form high spin complexes.
(ii) Refer to answer 63.
electrons are present in 3d-orbitals of Ni-atom 71. (i) Oxidation state of Co ion in (CoFJ is
hence, this complex is paramagnetic in nature. +3.
On the other hand, due to the presence of strong 3d 4s

field ligand i.e, CN in the complex [Ni(CN),J², Co":[|1uOO

(In ground state)
no unpaired electron is present in 3d-orbitals of
Ni-atom (as strong field ligand causes pairing of
[CoF]-:
3d0 46 4p 4d
electrons), hence, it is diamagnetic in nature.
(b) In tetrahedral coordination entity formation,
sp'Phybridisation
the d-orbital splitting is smaller. Consequently, six pairs of electrons
from six Fion
the orbital splitting energies are not sufficiently
(Weak ligands )
large to force pairing and therefore, low spin
configurations are rarely observed. Structure - Outer orbital octahedral complex
68. Fe atom (Z = 26)
F 3
4p
Ground state: [|t34
46 1p
Nature - Paramagnetic
Fe' ion : (i) In (Ni(CN),J2-: Niis present as Ni(l) with
3d' configuration.
(Fe(CN).|" ion (11|1|1 e opeoe
dsp hybridisation
(strong ligand) (In ground state)
[NiCN),J² : 1 1 | 1 | | I 77. Refer to answer 74.
dsp' hybridisation 78. Refer to answer 71(ii).
four electrons pairs 79. In presence of CN, the 3d electrons pair
donated by four
CN ions up leaving only one unpaired electron, the
(Strong ligand) hybridisation is dsp forming an inner orbital
The complex ion has square planar geometry and octahedral complex whereas in the presence
is diamagnetic in nature. of H,0, 3d electrons do not pair up. The
72. Refer to answer 71 (i). hydridisation is sp'd forming an outer orbital
IUPAC Name: Hexafluoridocobaltate(III) ion octahedral complex containing five unpaired
73. Refer to answer 71(i). electrons. Hence, it is strongly paramagnetic.
IUPAC name : Tetracyanidonickelate(Il) ion 80. (i) [Co(NH),CIJCl,: Pentaamminechlorido
74. Oxidation of cobalt in[Co(NH,).]" is +3. cobalt (III) chloride.
3d
Co(I) : [Ar]3°4s° : dPsp' hybridisation leads to
Cot: octahedral shape.
Ground State Magnetic behaviour : Diamagnetic.
Stereochemistry : Complex [Co(NH),CIJCI, do
[Co(NH,)] ion : 11|1 not exhibit geometrical and optical isomerism.
d'sp' hybridisation (ii) K,[Ni(CN),J:Potassiumtetracyanidonickelate(II)
six pairs of electrons
from six NH, ligand Ni(1) : (Ar] 34 - dsp' hybridisation leads to
(Strong ligand) square planar shape.
Magnetic behaviour : Diamagnetic.
Hybridisation - d'sp'
Structure -Octahedral NH,
H,NyNH, Stereochemistry : Complex [Ni(CN)J) do no
(low spin) exhibit geometrical isomerism and optical
Nature - Diamagnetic 0somerism because all the possible arrangement
NH, are equivalent.
IUPAC name : Hexaamminecobalt(III) ion
81. () [Fe(H,0) J2+:
75. () [Co(en),Cl(NH)] Fe atom (Z= 26)
Amminechloridobis(ethane-1,2-diamine)cobalt(III) 3/0 46
ion Ground state : (1|1|
In presence of strong NH, and en ligand, Co 4s

(3d") forms low spin complex. Hence, complex is Fe*ion:

diamagnetic.
[Fe(H,0)J2:
(i) [Ni(C,0,),(H,0),1: 3d 4s 40
Diaquadioxalatonickelate() ion
In the presence of weak H,0 and ox ligand, Ni(II)
forms high spin complex (sp°d hybridisation). It sp'd'hybridisation
is paramagnetic. six pairs of electrons
76. (i) In presence of strong field ligand, Co(l1) from six H,0 ligands
(weak ligand)
has electronic configuration te. The complex ion has outer orbital octahedral
- A, > P
geometry (high spin) and is paramagnetic due to
the presence of four unpaired electrons.
(ii) Refer to answer 71 (i).
It can easily lose one electron present in e, orbital
to give stable t§, configuration. This is why Co is 82. Tetrachloridonickelate(1I) ion
easily oxidised to Co in the presence of strong Ni atom (Z= 28)
field ligand. 3d 4p
(ii) Refer to answers 71(ii) and 63. Ground state: (11|1|1 1
 3d 4s Tetraamminedichloridocobalt (II) chloride
It is octahedral and diamagnetic.
Ni ion: (TL|11|1|1|D
(ii) Ni(CO),: Tetracartbonylnickel(0)
[NiCLP : 1|11|| It is tetrahedral and diamagnetic.
sp hybridisation 85. (1) [Fe(CN),] :Hexacyanidoferrate(II) ion
four pairs of electrons Hybridisation -d²sp'
from four Ct ligands
(weak ligands) Structure : Inner orbital octahedral complex
The complex ion has tetrahedral geometry and
is paramagnetic due to the presence of unpaired
electrons.
83. The difference of energy between two splitted Octahedral
levels of d-orbitals is called crystal field splitting
energy. It is denoted by Aor 10 Dq. (i) (Cr(NH),CJ":
For octahedral A,, for tetrahedral it is A, and for Tetraamminedichloridochromium() ion
square planar A, Hybridisation -#sp'
Structure : Inner orbital octahedral complex
Degenerate Aor 10 Dq NH;
d-orbitals
Splitted d-orbitals C
(i) When A, > P, e Octahedral
(ii) When A, <P, e (iii) [Ni(CN)J² :Tetracyanidonickelate(lI) ion
Hybridisation -dsp²
84. (i) [Pt(NH),CI(NO,)] : Structure- Square planar
Diamminechloridonitrito-N-platinum(1)
t is square planar and diamagnetic. NC CN

() (Co(NH),C,]CI: NC CN
Square planar
86

Formulae Name of the Complex Hybridisation Geometry of Magnetic

of metal complex behaviour
ion involved (stereochemistry)
) K,[Mn(CN).] Potassium hexacyanidomanganate(II) d'sp' Octahedral Paramagnetic
()|[Co(NH),Cl|C, Pentaamminechloridocobalt(III) chloride d'sp' Octahedral Diamagnetic
|(i) K,(NI(CN)J Potassiumtetracyanidonikelate (II) dsp Square planar Diamagnetic
None of these complexes will show stereoisomerism.
87. (i) [Fe(en),Cl,]CI CI CI
x+0x2 +(-1) x 2+ (-1) x 1 =0
.. x= +3
Oxidation number of iron = +3
Len
(i) 'sp' hybridisation and octahedral shape. CI
(iii) Paramagnetic due to presence of one trans-bis(ethanc-1,2-diaminc) cis-bis(ethane-1,2-diamine)
dichloridoiron(II) chloride dichloridoiron(II) chloride
unpaired electron.
(iv) 2, cis- and trans-isomers. (v) cis-(Fe(en),Cl,] has optical isomer.
 o donor as well as I acceptor by back bonding.
Hence, M-CO bond is stronger.
MCO
en NH, 0s electron pair donor only. Accumulation of
dextro Mirror laevo
negative charge on the metal ion takes place, hence
(vi) dichloridobis(ethane- 1,2-diamine)iron(I) M-NH, bond is weaker.
chloride M- NH,
88. 90. Refer to answer 89,
Complex Cen-Hybridi- Geom- Mag 91. Because CO has vacant molecular orbitals
tral sation of etry of netic
metal metal com behay with which it can form r-bond with metal through
ion/ ion in plex iour
back donation.
atom volved 92. (i) Na,EDTA is used for estimation of
d'sp Octa- Para hardness of water.
hedral magnetic (ii) Wilkinson's catalyst is used as catalyst for
()(Co(en),jCl, Co #sp |Octa- Diamag
hedral netic hydrogenation.
93. cis-Platin is used in the treatment of cancer.
(t) K,[Ni(CN),I N dsp Square Diamag EDTA is used in lead poisoning.
planar netic
89. In CO both lone pair of electronsand vacant r*
orbitals are present. Hence, it acts as electron pair