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Coordination compounds

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Coordination compounds

•Ligands and its classification •Central metal atom •oxidation state •coordination number •Ionisation and coordination sphere

WERNERS THEORY OF COORDINATION COMPOUNDS

• 1. METAL ATOM EXIBITS TWO TYPES OF VALENCIES.

IONISABLE VALENCY (PRIMARY)

NON IONISABLE VALENCY (SECANDARY)

2. SECANDARY VALENCY IS FIXED AND IS EQUAL TO

CO ORDINATION NUMBER.

3. SECANDARY VALENCIES ARE DIRECTED TOWARDS FIXED POSSITION IN SPACE ARROUND METAL ION HENCE COMPLEX ION EXIBITS STEREO ISOMERISM

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ISOMERISM

ISOMERISM

Same formula and different

properties

STRUCTURAL

Different bonds

LINKAGE

IONISATION

HYDRATE

COORDINATION

STEREO

Different spatial

arrangement

OPTICAL

GEOMETRICAL

NOMENCLATURE • In ionic complexes the cation is named

first and then the anion.

• Neutral complexes are named in one word.

• In naming the co-ordination sphere the ligand are named first and followed by central metal ion.

• Anionic ligands: Anionic ligands ending with ‘ide’ are named by replacing ‘e’ ‘by ‘o’

• The ligands are named in an alphabetical order of preference.

• If there are several ligands of the same type [monodentate] are named using the prefix di , tri , tetra , penta etc.

• When the name of ligands include a numerical prefix then the term bis (2 ligands) tris (3 ligands), tetrakis (4 ligands) are used.

• After naming all the ligands central metal ion is named.

• In case of cationic complex or neutral complex, the name of the metal is retained as such.

• In case of anionic complexes, the name of the metal is ended with ate, preferably selecting the Latin name of the metal.

• After naming the metals, its oxidation state is indicated in Roman numerals in parenthesis

Types of hybridization Shape 1. dsp2 hybrdization Square planar 2. sp3 hybridization Tetrahedron 3. d2sp3 hybridization Octahedron

Valence bond theory (VBT)

Crystal Field Theory Assumptions

Ligands: negative point charges Metal-ligand bonding: entirely ionic

strong-field (low-spin): large splitting of d orbitals

weak-field (high-spin): small splitting of d orbitals

Crystal field splitting in octahedral coordination entities

Crystal field splitting in octahedral coordination entities

High spin Low spin

Crystal field splitting in octahedral coordination entities

Complimentary colors and its wavelength

Complimentary colors and its wavelength

Crystal field splitting in octahedral coordination entities

complex species

No. of unpaired

d -electrons

CN and OS of central metal

atom

magnetic character and Calculation

of magnetic moment

Reaction data Identification

of formula

Valence bond theory

Crystal field theory

a) FeSO4 , K4[Fe(CN)6]

b) [Cu(NH3)4]SO4 , FeSO4 .7H2O

c) [Cu(NH3)4]SO4 , K2 SO4Al2(SO4)3 .24H2O

d) MgSO47H2O, CuSO4

ANSWER

1. Which of the following pair contains complex salt and double salt respectively?

a) oxidizing agent

b) Lewis acid

c) solvent

d) ligand

ANSWER

2. In the reaction Cu 2++ 4NH3→[Cu(NH3)4]2+(aq),

Cu 2+ is acting as a(n)

a)2

b)3

c)4

d)5

ANSWER

3. The number of moles of ions formed in 1M solution of Potassium hexacyanidoferrate(II) would be

K4 Fe(CN)6 4K+ + 1 [Fe(CN)6 ] 4-

POTASSIUM FERROCYANIDE

4.which one of the following is a cationic complex compound ?

a)[Ag(NH3)2]Cl

b)[Mn(CN)6]K4

c)[Fe(CN)6]K4

d) K3 [Fe(CN)6]

ANSWER

[Ag(NH3)2]Cl - [Ag(NH3)2] + + Cl -

a) ON = 1, CN = 1

b) ON = 1, CN = 2

c) ON = 2, CN = 2

d) ON = 2, CN = 4

ANSWER

5.What are the oxidation number (ON) and coordination number (CN) in the coordination compound, [Cu(en)(NH3)2]Cl2?

[Cu(en)(NH3)2]Cl2 [Cu(en)(NH3)2] +2 + 2Cl-

X + 0 (1) +(0 )(2) = +2

O S = X = +2

[Cu(en)(NH3)2]Cl2

(ethylene diammine bidentate ligand + two monodentate ligands)

CO. NO. = 2+2 = 4

a) [Pt(NH3)2Cl2]

b) [Cr(CO)6]

c) [Cr(NH3)3Cl3]

d) [Cr(en)2Cl2]

ANSWER

6.In which of the following complexes the oxidation number of the central metal atom is zero ?

a)3

b) 5

c) 6

d) 4

ANSWER

7.How many d- electrons are in the cobalt ion of K3[Co (CN)6]?

27 Co

a)4 and 6

b) 3and 6

c)6 and 4

d)6 and 3

ANSWER

PtCl2 4NH3 and CoCl3 4NH3 on treatment with excess of AgNO3 solution gives two and one moles of AgCl precipitate respectively. The secondary valency of the metal ion in these complexes are respectively

PtCl2 4NH3 2 AgCl - [Pt (NH3)4 ] Cl2 CoCl3 4NH3 1 AgCl - [Co (NH3)4 Cl2 ] Cl

[Pt (NH3)4 ] Cl2

[Co (NH3)4 Cl2 ] Cl

a)[Cr(NH3)5 SO4 ]Cl

b)[Co(NH3)4 Cl2]NO2

c)[Cr(NH3)5 Cl ]SO4

d) K4 [Fe (CN)6]

ANSWER

9.Which of the following complex will give white precipitate with Barium chloride solution ?

a)[Co(NH3)3Cl3 ]

b)[Co(NH3)4Cl2 ]Cl

c)[Co(NH3)5Cl ]Cl2

d)[Co(NH3)6 ]Cl2

ANSWER

10.Which of the following is non ionisable?

(a) + 1 (b) + 2 (c) + 3 (d) 0

11.In the test for nitrate in, the brown ring formed has a formula [Fe(H2O)6NO]SO4. The oxidation number of iron in this complex is

ANSWER

[Fe(OH2)6 NO] SO4

[Fe(OH2)6 NO] 2+ + SO4 2-

X(1)+6(0) + 1(0)=+2 hence x = +2

12.In the complex compound,

[Co(NH3)6 ] [Cd Clx ] the oxidation number of cobalt is + 3. The values of x is (a) 3 (b) 4 (c) 2 (d) 5

ANSWER

[Co(NH3)6 ] 3+ [Cd Clx ]

3-

+2(1) + x(-1)=-3 +2 – x = -3 x = 5

[Co(NH3)6 ] [Cd Cl5 ]

IUPAC NAMENCLATURE

a)K3[Al(C2O4)3]

b) K2[Al(C2O4)3]

c) Al [K3 (C2O4)3]

d) K[Al(C2O4)3]

ANSWER

13.The formula of potassium trioxalatoaluminate(III) is

[ Al (C2O4) 3 ] K3

ANSWER

14.Which name-formula combination is NOT correct? FORMULA NAME

(I) [Co(NH3)4(OH2)I]SO4 tetraammineaquaiodidocobalt(III)

sulphate

(II) K[Cr(NH3)2Cl4] potassium

diamminetetrachloridochromate(III)

(III) [Mn(CN)5]2- pentacyanomanganate(II) ion

(IV) Ca[PtCl4] calcium tetrachloridoplatinate(II)

a)I b)II c)III d) IV

a)Chloridonitrito-Nbis(ethylenediamine) cobaltic (III) chloride b)Chloridonitrobis(ethylenediamine) cobalt (II) chloride c)Chloridobis(ethylenediamine)nitrito-Ncobalt (III) chloride d)bis(ethylenediamine)Chloridonitro cobalt (III) chloride

ANSWER

15.The IUPAC name of [CoCl(NO2)(en)2]Cl is

a)Potassium tetrahydroxy zinc (II)

b)Potassium tetrahydroxidozincate (II)

c) Potassium tetrahydroxy zinc (0) d)Potassium hydroxo zinc (II)

ANSWER

16.The correct IUPAC name of K2[Zn(OH)4] is

a)Al[LiH4]

b)Al2[LiH4]3

c)Li[AlH4]

d)Li[AlH4]2

ANSWER

17.Lithium tetrahydrido Aluminate is correctly represented as

(a) Triamminebromidochloridonitrito-Nplatinum (IV) chloride

(b) Triamminenitrochlorobromoplatinum (III) chloride

(c) Triamminebromonitrochloroplatinum (IV) chloride

(d) Triamminebromodichloronitroplatinum (IV)

ANSWER

18.The IUPAC name of the compound [Pt(NH3)3Br(NO2)Cl] Cl is

ISOMERISM

a)Linkage isomerism b)Ionisation isomerism c)co-ordiantion compounds d)solvate isomerism

ANSWER

19.The two compounds Sulphatopentaminecobalt(III) bromide & pentaminechlorocobalt(III) sulphate, represents

pentamminesulphatocobalt(III) bromide [Co(NH3)5 SO4] Br

pentamminechlorocobalt(III) sulphate [Co Cl (NH3)5] SO4

a)coordination isomers

b)optical isomers

c)linkage isomers.

d)geometric isomers

ANSWER

20.The complex ions I.[Co(NH3)4(NO2)Cl]+ II. [Co(NH3)4(ONO)Cl]+ are:

a)Geometrical and Ionization

b)Geometrical and Optical

c)Optical and Ionization d)Geometrical only

21.Which kind of isomerism is exhibited by octahedral Co(NH3)4 Br2 Cl

Co(NH3)4 Br2 Cl

[Co(NH3)4 Br2 ]Cl

[Co(NH3)4 Br Cl] Br

M X4 Y2

ANSWER

a)[Pt(NH3)2Cl2] - (square planar)

b)[Zn(NH3)2Cl2] - (tetrahedral)

c)[Cu(NH3)4]2+ - (square planar) d)[Co(NH3)5Cl]2+ - (octahedral)

ANSWER

22.Which one of the following complexes can exhibit geometrical isomerism?

a)3.87BM

b) 2.87BM

c)4.89BM

d)5.92BM

ANSWER

23.The spin magnetic moment of Cobalt in compound K [Co(SCN)4] is

27 Co 1s2 2s2 2p6 3s2 3p6 4s2 3d7

Oxidation state of Co in this complex is +3 Electronic configuration of Co +3 is 1s2 2s2 2p6 3s2 3p6 3d6 with four unpaired electrons. µ= √n(n + 2)= √24 = 4.89 BM

↑↓ ↑ ↑ ↑ ↑

(a) [FeF6]3-

(b) [Co (NH3)]3+

(c) [Fe(CN)6]4-

(d) [Mn(CN)6 ]4-

ANSWER

24.Which of the following has highest magnetic moment ?

I- < F- ≤ OH- , ONO- < OH2 < NCS- < NH3 <NO2

- < CN- , CO weak-field ligands strong-field ligands

[FeF6]3- 26Fe3+ 3d5 5 WFL HIGH SPIN

5e

[Co (NH3)]3+ 27Co3+ 3d6 4 SFL LOW SPIN

0e

[Fe(CN)6]4-

26Fe2+ 3d6 4 SFL LOW SPIN

0e

[Mn(CN)6 ]4-

25Mn2+ 3d5 5 SFL LOW

SPIN 1e

(a) [Ni(CO)4]

(b)[Fe(CN)6]4-

(c) [CoF6]3-

(d) [MnF6]3-

ANSWER

25.Which of the following complexes is inner orbital complex ?

I- < F- ≤ OH- , ONO- < OH2 < NCS- < NH3 <NO2

- < CN- , CO weak-field ligands strong-field ligands

[Ni(CO)4] 28 Ni0

3d8 sp3 SFL No pairing

of e

[Fe(CN)6]4- 26Fe2+

3d6 d2sp3 SFL Pairing of e

[Co(F)6]3-

27 Co3+ 3d6 sp3d2 WFL No pairing of e

[Mn(F)6 ]3-

25Mn2+ 3d5 sp3d2 WFL No pairing

of e

(a) 1, 4 (b) 1, 2, 5 (c) 2, 3, 5 (d) 2, 3

26. The coordination complex, [Cu(OH2)6]2+ has one unpaired electron. Which of the following statements are TRUE? 1)The complex is octahedral. 2) The complex is an outer orbital complex. 3) The complex is d2sp3 hybridized. 4) The complex is diamagnetic. 5) The coordination number is 6.

ANSWER

TRUE

TRUE

FALSE

TRUE

FALSE

27.Nickel (z=28) combines with a uninegative monodentate ligand X- to form a paramagnetic complex [NiX] 2-. The number of unpaired electrons in nickel and geometry of this complex ion are respectively

a)one, tetrahedral b)two, tetrahedral

c)one, square planar d)two, square planar

ANSWER

28 Ni- 1s2 2s2 2p6 3s2 3p6 4s2 3d8

Oxidation state of Ni in this paramagnetic complex is +2 Electronic configuration of Ni+2 is 1s2 2s2 2p6 3s2 3p6 3d8 with two unpaired electrons. 3d 4s 4p

↑↓ ↑↓ ↑↓ ↑ ↑

(a)3.87BM

b)2.87BM

c)4.89BM

d)5.92BM

ANSWER

28.The calculated spin magnetic moment of iron in compound K4[Fe(CN)6] is

26 Fe- 1s2 2s2 2p6 3s2 3p6 4s2 3d6

Oxidation state of Fe in this complex is +2 Electronic configuration of Fe +2 is 1s2 2s2 2p6 3s2 3p6 3d6 with four unpaired electrons. µ= √n(n + 2)= √24 = 4.89 BM

↑↓ ↑ ↑ ↑ ↑

(a) d7 (high spin)

(b) d9 (high spin)

(c) d6 (low spin)

(d) d4 (low spin)

ANSWER

29.Which of the following system in octahedral complex has unpaired maximum electrons ?

WFL AND NO PAIRING

WFL AND NO PAIRING

SFL AND PAIRING

SFL AND PAIRING

(a) Na2 [CuCl4]

(b) Na2 [CdCl4]

(c) K4 [Fe(CN)6]

(d) K3 [Fe(CN)6]

ANSWER

30.Which of the following compound is not coloured ?

METAL ION

ELECTRONIC CONFIGURATION

29Cu 2+ [Ar] 3d9 4s0

48Cd 2+ [Ar] 3d10 4s0

26Fe 2+ [Ar] 3d6 4s0

26Fe 3+ [Ar] 3d5 4s0

(a)d1 and d2

(b) tg and e2g

(c) eg and t2g

(d) fg and f2g

ANSWER

31.In octahedral field of ligands, the d-subshell splits up into 2 set of orbitals, which are designated as

(a)d1 and d2

(b) tg and e2g

(c) eg and t2g

(d) fg and f2g

(a) ∆ t = 4/9 ∆o

(b)∆ t = 0.5 ∆o

(c) ∆t = 9/4 ∆o

(d) ∆ t = 5/3 ∆o

ANSWER

32.The crystal field splitting energy for octahedral complex (∆0) and tetrahedral complex (∆ t) are related as

a)[Co(C2O4)3]3–

b) [Co(H2O)6]3+

c)[Co(NH3)6]3+

d) [Co(CN)6]3–

ANSWER

33.In which of the following octahedral complexes of Co (at no. 27), will the magnitude of ΔO be the highest?

a) 0

b) 6

c) 2

d) 4

ANSWER

34.How many unpaired electrons are there in a strong field iron(II) octahedral complex?

26 Fe- 1s2 2s2 2p6 3s2 3p6 4s2 3d6

Oxidation state of Fe in this complex is +2 Electronic configuration of Fe +2 is 1s2 2s2 2p6 3s2 3p6 3d6 with four unpaired electrons. In strong field pairing of e occurs

↑↓ ↑ ↑ ↑ ↑

↑↓ ↑↓ ↑↓

a) usually produce high spin complexes and small crystal field splittings.

b) usually produce low spin complexes and small crystal field splittings.

c) usually produce low spin complexes and high crystal field splittings.

d) usually produce high spin complexes and high crystal field splittings.

ANSWER

35.Strong field ligands such as CN-:

a)

b)

c)

d)

ANSWER

36.Based on the crystal-field strengths which Co(III) complex is most likely high-spin?

22 3

- - -F CH CN NH NO CN

3

3 6[Co(NH ) ]

3

2 6[Co(NO ) ]

3

6[Co(CN) ]

3

6[CoF ]

a)X = [ Au ( CN) 2] - and Y = [ Zn (CN) 4 ] 2-

b) X = [ Au ( CN) 4] 3 - and Y = [ Zn (CN) 4 ] 2-

c) X = [ Au ( CN) 2] - and Y = [ Zn (CN) 6 ] 4- d) X = [ Au ( CN) 4] - and Y = [ Zn (CN) 4 ] 2-

ANSWER

37.In the process of extraction of gold, Roasted gold ore Identify the complexes [X] and [Y]

OH[X]OHCN 2O2

Au[Y]Zn[X]

a)Cyanocobal amine (vitamin B12 ) contains cobalt b)Haemoglobin contains iron c)Chlrophyl contains calcium d)Carboxypeptidase A contains zinc

ANSWER

38.Co-ordination compounds have great importance in biological systems in this context, which of the following statements is incorrect?

a)Vitamin B12

b)Chlorophyl

c)Haemoglobin

d)Insulin

ANSWER

39.Which of the following biomolecules contains non transition metal ion ?

Co

Mg

Fe

Zn

a)[Co (NH3)3 Cl3]2NH3 b)[Co (NH3)4 Cl2]NH3Cl c)[Co (NH3)4 Cl]Cl2NH3 d)[Co (NH3)5 Cl]Cl2

ANSWER

40. One mole of complex compound Co(NH3)5 Cl3 gives 3 moles of ions on dissolution in water . One mole of the same complex reacts with 2 moles of AgNO3 solution to give 2 moles of AgCl . The structure of complex is

Co(NH3)5 Cl3 - 2AgCl [Co (NH3)5Cl] 2+ + 2Cl- [Co (NH3)5Cl]Cl2

a)0.001

b)0.002

c) 0.003

d) 0.01

ANSWER

41.An excess of AgNO3 is added to 100 mL of a 0.01 M solution of dichlorotetraaquachromium(III) chloride. The number of moles of AgCl precipitated would be

[Cr (H2O)4 Cl 2] Cl NO. of moles of Cl formed on dissociation is = 0.01/100 = 0.001

a)The 3d orbitals in Cu+ are completely empty so the transfer of an electron cannot occur. b)The 3d orbitals in Cu2+ are completely filled so the transfer of an electron can occur. c)The 3d orbitals in Cu+ are completely filled so the transfer of an electron cannot occur. d)Cu+ absorbs all wavelengths of visible light which makes it appear colorless.

ANSWER

Which of the following best explains why coordination compounds containing Cu2+ are colored but coordination compounds containing Cu+ are not?

29 Cu+- 1s2 2s2 2p6 3s2 3p6 4s 3d10 4s0

29 Cu+2- 1s2 2s2 2p6 3s2 3p6 4s 3d9 4s0

↑↓ ↑↓ ↑↓ ↑↓ ↑↓

↑↓ ↑↓ ↑↓ ↑↓ ↑

42.The calculated magnetic moment for

K n[V(ox)3] complex compound is 2.82 BM. What is the value of n in the formula? (ox2– = oxalate ion)

a) 2

b) 1

c) 3

d) 4 ANSWER

No. of unpaired electrons

μ = √n (n+2)BM Vanadium Z = 23

3d34s2

0 0

1 √3 = 1.73

2 √8 = 2.82

3 √ 15 = 3.87

4 √ 24 = 4.89

5 √ 35 = 5.91

μ = 2.82 BM means vanadium has two unpaired electrons with an oxidation state

of +3 3d2

let the charge on the complex ion be X Then X = 1(+3) + (-2) 3 =+ 3 - 6 =-3 To balance -3 charge put 3 K+ ions Hence n = 3 K3 [ V ( OX)3 ]

K3 [ V ( OX)3 ]

43. How many unpaired d- electrons are present in the central metal ion of K3[Co(CN)6]?

a) 3

b) 5

c) 4

d) 6

K3[Co(CN)6] Oxidation state of cobalt in this complex is +3 Electronic configuration of Co is 3d7 4s2

Electronic configuration of

Co 3+ 3d6

ANSWER

44.What is the oxidation number of chromium in [Cr(en)2(NH3)2]Cl3?

a)-3

b)+3

c)+2

d) -2

[Cr(en)2(NH3)2] Cl3

[Cr(en)2(NH3)2] +3 + 3 Cl -

X + 0 (2) +(0 )(2) = +3

X = +3

ANSWER

45. One mole of complex compound Co(H2O)5 Cl3 gives 3 moles of ions on dissolution in water . One mole of the same complex reacts with 2 moles of AgNO3 solution to give 2 moles of AgCl . The structure of complex is

a)[Co (H2O)3 Cl3].2H2O

b)[Co (H2O)4 Cl2]Cl .H2O

c)[Co (H2O)4 Cl]Cl2 H2O

d)[Co Cl (H2O)5]Cl2

Co(H2O)5 Cl3 → [Co Cl (H2O)5 ] +2 + 2Cl –

( 3 moles) 2AgNO3

Co(H2O)5 Cl3 + 2AgNO3 → 2 AgCl (2 moles)

Formula of the complex is [Co Cl (H2O)5 ] Cl2

ANSWER

46. The calculated spin magnetic moment of iron in compound K4[Fe(CN)6] is

a) 3.87BM

b) 2.87BM

c) 4.89BM

d) 5.92BM

K4[Fe(CN)6] CENTRAL METAL ION IS Fe OS IS +2 ELECTRONIC CONFIGURATION OF IRON IS [Ar] 3d64s2

ELECTRONIC CONFIGURATION OF Fe 2+ IS [Ar] 3d6

CONTAINS 4 UNPAIRED ELECTRONS. µ= √n(n + 2)= √24 = 4.89 BM

↑↓ ↑ ↑ ↑ ↑

ANSWER

0.02 mole of and

0.02 mole of was mixed and made up to 2L by adding water.

1 litre of above mixture + excess AgNO3 → Y

1 litre of above mixture + excess BaCl2→ Z Number of moles of Y and Z are

a)0.01 & 0.01

b)0.02 & 0.01

c)0.01 & 0.02

d)0.02 & 0.02

BrSONHCo ])([ 453

453 ])([ SOBrNHCo

[Co SO4 (NH3)5 ]Br (0.02 mole)/2L = 0.01mol/L 1 litre of above mixture +excess AgNO3 →0.01 mol/L

of AgBr (Y)

[Co Br (NH3)5 ] SO4 (0.02 mole)/2L = 0.01mol/L

1 litre of above

mixture +excess BaCl2 →0.01 mol/L of BaSO4

(Z)

ANSWER

a)287 × 10–3 b)143.5 × 10–3

c)143.5 × 10–2 d) 2.87

ANSWER

Excess of silver nitrate solution is added to 100 ml of 0.01 M Pentaaquachloridochromium(III) chloride solution. The mass of silver chloride obtained in grams is [Atomic mass of silver is 108].

[Co(H2O)5 Cl]Cl2

[Cl] = 2 x 0.01 = 0.02M [AgCl] = 0.02 Mass of AgCl = 0.02 x (108 +35.5) = 2.87

(a) 80 ml (b) 40 ml (c) 20 ml (d) 120 ml

In the complex MCI3.5H2O, the co-ordination number of the metal M is six and there is no molecule of hydration. Then the volume of 0.1 M AgNO3 solution needed to precipitate the free chloride ions in 200 ml of 0.01 M solution of the complex is

ANSWER

MCI3.5H2O [M(H2O)5 CI ] CI2

200 ml of 0.01 M solution contains 200ml of 0.02 molar chloride ions. M1V1 = M2 V2

0.02 X 200 = 0.1 X V2

V2 = 40mL

CI3 CI3

a)[Cu(NH3)4]2+

b)[Ni(CN)4]2–

c) TiCl4

d) [CoCl6]3– ANSWER

47. which one among the following show magnetic moment of 1.73 BM ?

Cu 2+ 3d 9 1e

Ni 2+ 3d 8 2e

Ti 4+ 3d 0 0e

Co 3+ 3d 6 4e

a) SCN-

b) CN-

c) 2, 2-Dipyridyl

d) OH-

ANSWER

Which among the following represent chelating ligand ?