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Inorganic Chemistry Lab report , Experiments Raw Data · January 2015 DOI: 10.13140/RG.2.1.1119.6568

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Muhammad Yasir Siddique

Government College University Faisalabad

University of Gujrat

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Experiment No. 1 Determination of Nickel with Dimethylglyoxime (DMG). 1.1

Principle:This is a gravimetric analysis. Principle behind gravimetric analysis is that the mass of

an ion in a pure compound can be determined and then used to find the mass percentage of the same ion in a known quantity of an impure compound.

1.2

Theory:Gravimetric analysis is one of the most accurate analytical methods. This is concerned

with the determination of a substance by the process of weighing. The element or radical to be determined is converted into a stable compound of definite composition and the mass of the compound is determined accurately. From this, the mass of element or radical is calculated. The gravimetric analysis involves precipitation, filtration, washing of the precipitate, drying, ignition and weighing of the precipitates.

1.3

Apparatus & Chemicals:Burette, pipette, cylinder, stand, spirit, lamp, titrating flask, beaker Water, DMG (1%), NH3 solution (50%0, NiSO4 (0.1M)

1.4

Chemical Equation:-

Structure of DMG & the complex with nickel ions is given below

1

1.5

Procedure:Took 20 ml of NiSO4 solution in 400 ml of beaker. Added 150 ml of distilled water in

it and heat up to 70-80°C.Now added 30 ml of 1%DMG solution. Added ammonia solution, upon adding ammonia precipitates are formed and added until no more ppt.is formed. Kept it for 30 minutes to settle down the ppt, washed with hot water so that if there is any Ni uncomplexed or DMG, they will flow with water. Filtered the solution with whatman filter paper and ppt. are separated. Dried ppt.at 100°C in an oven and weight it for calculations.

1.6

Observations and calculations:Table 1.1

Weight of filter paper

= 1g

Weight of nickel complex + weight of filter paper

= 3.5 g

Weight of Dimethylglyoxime nickel complex

= 2.5 g

288.69 g of nickel complex contain nickel

= 58.69 g

1 g of nickel complex contain nickel

= 58.69/288.69 g

2.5 g of nickel complex contain nickel

= 58.69 x (2.5)/288.69 g = 0.50g

1.7

Solubility of Ni-DMG Complex:-

Table 1.2 S.No

Solvent

Solubility

1.

Water

Insoluble

2.

Methanol

Soluble

3.

Ethanol

Soluble

4.

Chloroform

Insoluble

2

1.8

Properties of DMG:Table 1.3

Molecular formula

C4H8N2O2

Formula mass

116.12

Density

1.037 gcm-3

Melting point

240-241 °C

1.9

UV-Visible, IR, NMR Spectra:UV Spectra of NI-DMG:The interpretation of different spectras like UV,IR, NMR are given here, 2.0

Smooth: 31

ABS

Deri.: 0

1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0

nm 200

250

300

350

400

450

500

550

600

650

700

750

Table 1.4 Complex

λmax (nm)

Ni-DMG

233

3

800

1.9.1

Interpretation of UV-Visible spectra:For UV-visible 0.001M solutions were prepared and spectra were taken. The Ni-DMG Complex show Maximum Absorbance at 233nm.the transition metal

in the complex has empty d orbital upon the absorbance of light in the range of visible light the lower laying electron in t2g is move toward eg orbital at higher energy so the transition of electron from t2g to eg called d-d transition due to which the compound show the colours. 1.9.2

Proton NMR for DMG:-

2

1

PPM

0

Two CH3 show peak at 1.90 ppm because both the CH3 has three protons decoupled and in same environment and two OH group show peak at 2.0 ppm.

1.9.3

Carbon NMR for DMG:-

160

140

120

100

80 PPM

60

40

20

0

This graph shows the 2 peaks, one peak is C and other for CH3 group.CH3 group is in the up field region and C in in the downfield region.

4

1.9.4

Carbon NMR for Ni DMG complex:-

180

160

140

120

100

80

PPM

60

40

20

0

In carbon NMR of nickel Ni (DMG)2 there are two peaks are.CH3 show peak which is upfield at 13.2ppm and Carbon show peak at 164ppm.

1.9.5

Proton NMR for Ni DMG complex:-

2

PPM

1

0

In proton NMR of Ni (DMG)2 complex only two peaks are visible. Four methyl groups are chemically equivalent and showing only one peak, which is up field at 1.90ppm. Other single peak is due to four hydroxyl groups because they are in same chemical environment and no any neighboring proton is present for splitting.

5

1.10

Results & Discussion:It was gravimetric type of analysis in which nickel DMG complex is formed. Ppt. are

formed, weighed out and made calculations. Solubility of complex is checked with water, ethanol, methanol and Chloroform. Soluble in ethanol, methanol insoluble in water. For UV-Visible studies 0.001M solutions were prepared and spectra were studied that give the Lambda max value at 233nm the range of UV-visible is 180-800nm. The NiDMG Complex show Maximum Absorbance at 233nm.the transition metal in the complex has empty d orbital upon the absorbance of light in the range of visible light the lower laying electron in t2g is move toward eg orbital at higher energy so the transition of electron from t2g to eg called d-d transition due to which the compound show the colours. The NMR spectra of both complex and Ligand was taken both are the different from each other giving the different peaks of proton and C at different value of Chemical shift that indicates the formation of the complex between the Transition metal and Ligand in 1:2. IR spectra Of Ni-DMG gives the different information about the complex. The IR range is from 12500cm-1 to 10cm-1. It is divided into three regions, Near IR region, Mid IR region, Far IR Region having range 12500-4000cm-1, 4000-200cm-1 and 200-10cm-1 respectively. Mostly Used region is id IR Region that is further divided into functional group region 4000-1600cm-1 and finger print region 1500-650cm-1. IR region tell us about the O-H, N-H, C-H starching in 3700-2700cm-1 and C=C, C≡C in 2700-200cm-1C=O at 1700 cm-1. And most important peak C-M in range of 585-413 cm-1 is change according to nature of metal.

6

Experiment No. 2 Determine amount per dm3 of Al+3 by using 8hydroxyquinoline.AgNO3 as an organic reagent in a given sample solution. 2.1

Principle:In this analysis substance is analysed by weight. It is quantitative analysis.

2.2

Theory:Gravimetry includes measurement of mass, Here since precipitates are formed so, it is

precipitation gravimetric analysis. In this process counter ions come together and forms natural species which are usually in the form of precipitates. Gravimetry can be can be generalized into two types; precipitation and volatilization. The quantitative determination of a substance by the precipitation method of gravimetric analysis involves isolation of an ion in solution by a precipitation reaction, filtering, washing the precipitate free of contaminants, conversion of the precipitate to a product of known composition and finally weighing the precipitate and determining its mass by difference. From the mass and known composition of the precipitate, the amount of the original ion can be determined.

2.3

Chemicals & Apparatus:Al2 (SO4)3 (0.1M) Ammonia solution (10%) HCl solution (10%) Buffer (4.5-6.5) PH Burette, Beaker, Pipette, Funnel, Filter paper, Titrating flask, Stand, Cylinder

2.4

Chemical equation:Al3+ + 3 C9H6NOH → Al (C9H6NO) 3 + 3 H+

7

2.5

Structure:-

N

O

O

N Al

O N

2.6

Procedure:Took a beaker of 150 mL and added 20mL of sample solution in it. Added 5mL of

ammonia solution. The mixture of solution becomes turbid due to formation of Al (OH) 3. Added 10% HCl solution drop wise until solution becomes clear. Keep this solution for 30 minutes then cool the precipitates. Settled down them and then washed with hot water. Dried the precipitates at 100˚C in oven and weighed for calculations.

2.7

Yield of Complex:Table 2.1 Theoretical Yield (g)

Actual Yield (g)

% Yield

0.135

0.0128

48.41

8

2.8

Solubility:Table 2.2

2.9

S.No

Solvent

Solubility

1.

Water

Insoluble

2.

Methanol

Soluble

3.

Ethanol

Soluble

4.

Chloroform

Soluble

Interpretation of spectra:The interpretation of different spectra’s like UV, IR, NMR.

2.9.1

Proton NMR:

9

8

7

6

5 PPM

4

3

2

1

0

The proton NMR of this Tris-(8-hydroxyquinolinato) aluminium complex shows 5 peaks.one peak is reference peak. Other 4 peaks are more downfield because of attachment of nitrogen atom. A multiplet peak is at 6.9 is due to CH group in quinoline and splitting is due to neighbouring hydrogen atoms. Other 3 peaks are also multiplet due to splitting. A last peak at 8.9 is also due to CH group but it is more downfield because this group is very close to nitrogen. Benzene ring also shows reading more down field due to resonance.

9

2.9.2

Carbon 13 NMR:

160

140

120

100

80 PPM

60

40

20

0

A number of peaks appear in carbon NMR of Tris (8-hydroxyquinolinato) aluminium complex. The range of carbon NMR spectra is from 0-200 ppm. Among these 28 peaks about 8 peaks are due to only carbon atom, and remaining peaks are due to CH bond when H is irradiated in such a way that it does not affect the chemical shift value of 13C. 2.9.3

UV Spectra:2.0

Sm ooth: 25

ABS

Deri.: 0

1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0

nm 200

250

300

350

400

450

500

550

600

650

700

750

800

The maximum absorbance is observed at about 425 nm

Table 2.3 Complex

λmax (nm)

Tris (8-hydroxyquinolinato) aluminium

425

10

2.10

Discussion:It was gravimetric type of analysis in which Tris (8-hydroxyquinolinato) aluminium

complex is formed. Ppt. are formed, weighed out and made calculations. Solubility of complex is checked with water, ethanol, methanol and Chloroform. Soluble in ethanol, methanol, chloroform and insoluble in water. For UV-Visible studies 0.001M solutions were prepared and spectra were studied that give the Lambda max value at 425nm the range of UV-visible is 180-800nm. The Tris (8hydroxyquinolinato) aluminium Complex shows Maximum Absorbance at 425nm. The NMR spectra of both complex and Ligand was taken both are the different from each other giving the different peaks of proton and C at different value of Chemical shift that indicates the formation of the complex between the Transition metal and Ligand in 1:2. IR spectra Of Tris (8-hydroxyquinolinato) aluminum gives the different information about the complex. The IR range is from 12500cm-1 to 10cm-1. It is divided into three regions, Near IR region, Mid IR region, Far IR Region having range 12500-4000cm-1, 4000-200cm-1 and 200-10cm-1 respectively. Mostly Used region is id IR Region that is further divided into functional group region 4000-1600cm-1 and finger print region 1500-650cm-1. IR region tell us about the O-H, N-H, C-H starching in 3700-2700cm-1 and C=C, C≡C in 2700-200cm1

C=O at 1700 cm-1. In addition, most important peak C-M in range of 585-413 cm-1 is change

according to nature of metal.

11

12

THIOUREA COMPLEXES Thiourea is an organosulfur compound with the formula SC(NH2)2 . It is structurally similar to urea, except that the oxygen atom is replaced by a sulphur atom, but the properties of urea and thiourea differ significantly. Thiourea is a reagent in organic synthesis. Thiourea is related tothioamides, e.g. RC(S) NR2, where R is methyl, ethyl, etc.

It is the synthesis type of reaction in which Analysis is taken out gravimetrically. Weighing out the precipitates of resulting product. It is quantitative type of Analysis in which yield is being determined of complex that is formed through coordination between donor and receptor. It is complexometric type of reaction. Reaction takes place between metal and ligand. Coordination number of metal may be from 2-6 but for heavy metals it can be 8. Ligand attached to metal atom and satisfies its co-ordination number. Ligands can be classified as bidentate, tri, tetra and hexadentate depending upon their binding sites Chemistry of thiourea:

Thiocarbamide is a white powder or white/colourless crystals.



Thiocarbamide forms complexes with many metallic salts. It is produced by a reaction between Cyanamid and hydrogen sulphide or by a reaction between carbon disulphide and ammonia.

13

Experiment No. 3 Preparation of Tris-thiourea chromium(III) Chloride and determine % yield. 3.1

Principle:It is the synthesis type of reaction in which Analysis is taken out gravimetrically.

Weighing out the precipitates of resulting product. It is quantitative type of Analysis in which yield is being determined of complex that is formed through coordination between donor and receptor.

3.2

Theory: It is complexometric type of reaction. Reaction takes place between metal and

ligand. Coordination number of metal may be from 2-6 but for heavy metals it can be 8. Ligand attached to metal atom and satisfies its co-ordination number. Ligands can be classified as bidentate, tri, tetra and hexadentate depending upon their binding sites.

3.3

Chemicals & Apparatus: Chromium(III) Chloride hydrate, Thiourea, HCl, Distilled water Conical flask, Beaker, Stirrer, Filter Paper, Funnel, Watch glass, Glass Rod

3.4

Chemical equation:s CrCl3.6H2O +H2N

3.4.1

[Cr(thiourea)3]+3 Cl33-

C NH2

Ratio: 1:3 ratios of both chromium chloride Hydrate and thiourea is taken respectively. 3

thiourea molecules make dative bond with chromium.

14

3.5

Procedure:Prepared 1M soln. of CrCl6.H2O and thiourea respectively. Mixed 1:3 ratios of

both solutions as 10ml and 30ml of both respectively. Added few drops of 3M HCl. Heated the mixed solution until crystalline precipitates formed .Slurry obtained is dissolved in minimum of water at 50-60°C. Filtered it rapidly. Dried them and determined the yield.

3.6

Yield of complex Calculations: Table 3.1 Theoretical Yield (g)

Actual Yield (g)

% Yield

1.251

0.75

60

% yield

3.7

= actual yield/theoretical yield × 100 = 0.75/1.251×100= 60%

Solubility:Table 3.2 S.

Solvent

Solubility

1.

Water

Soluble

2.

Methanol

Sparingly

No

Soluble

3.

Ethanol

Sparingly Soluble

4.

Acetone

Sparingly Soluble

15

3.8

Properties of ligand:Table 3.3 Molecular formula

CH4N2S

Formula mass

76.12 gmol-1

Density

1.045 gcm-3

Melting point

162 °C

Thiourea is a planar molecule. The C=S bond distance is 1.60±0.1Å for thiourea (as well as many of its derivatives). The material has the unusual property of changing to ammonium thiocyanate upon heating above 130 °C. Upon cooling, the ammonium salt converts back to thiourea.

3.8.1

Structure:-

S

C

H N

HN

C

Cr

HN

NH

HN

NH C

S

16

S

Cl3-

3.9

Interpretation of Spectra:The interpretation of different spectra e.g. UV, IR, NMR.

3.9.1

Proton NMR:

2

1

PPM

0

Proton NMR of Tristhiourea chromium(III) Chloride complex shows only a single peak, which is due to NH group at 2.0 which is downfield due to electronegativity of nitrogen. 3.9.2

Carbon NMR:

200

180

160

140

120

100 PPM

80

60

40

20

0

In carbon NMR of Tristhiourea chromium(III) Chloride only a single peak is visible due to 3 carbon atoms having same chemical environment peak is downfield due to attachment of nitrogen atom which is electronegative. 3.9.3

IR spectra: The IR spectrum has been recorded in the range 400-4000 cm-1. In the IR spectra of chloro complexes, bands corresponding to ν(M–Cl) are observed

at 345–320 cm-1 indicating the presence of an M–Cl bond. The presence of bands at 1420– 1415, 1320–1280, and 1051–1018 cm-1, in the IR spectra of the nitrato complexes suggests that both nitrate groups are coordinated to the central metal ion in a unidentate manner.

17

3.9.4

UV spectra:Table 3.4 Complex

λmax (nm)

Tristhiourea chromium(III) Chloride

451

The name of the element chromium is derived from the Greek word, Chroma, meaning colour, because many of its compounds are intensely coloured. Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6. It has unfilled d orbitals in no 5 dxy dyz dzx dx2-y2 dz2. eg

t2 g 5 dxy dyz dzx dx2-y2 dz2

The Tristhiourea chromium(III) Chloride Complex show Maximum Absorbance at 451nm. The transition metal in the complex has empty d orbital upon the absorbance of light in the range of visible light the lower laying electron in t2g is move toward eg orbital at higher energy so the transition of electron from t2g to eg called d-d transition due to which the compound show the colours.

18

3.10

Discussion:This synthesis was gravimetric type of analysis in which after preparing solution we

followed a described procedure. The product is recrystallized by dissolving it in thiourea solution with few drops of sulphuric acid. After calculations we interpret the spectra of the complex e.g. NMR, IR UV spectra etc. Checked the solubility of the complex with water, ethanol, acetone etc. Explained the chemistry in terms of colour, structure and properties. For UV-Visible studies 0.001M solutions were prepared and spectra were studied that give the Lambda max value at 451nm the range of UV-visible is 180-800nm. The Tristhiourea chromium(III) Chloride aluminium Complex shows Maximum Absorbance at 451nm. The NMR spectra of both complex and Ligand was taken both are the different from each other giving the different peaks of proton and C at different value of Chemical shift that indicates the formation of the complex between the Transition metal and Ligand in 1:3. IR spectra Of Tristhiourea chromium(III) Chloride gives the different information about the complex. The IR range is from 12500cm-1 to 10cm-1. It is divided into three regions, Near IR region, Mid IR region, Far IR Region having range 12500-4000cm-1, 4000-200cm-1 and 200-10cm-1 respectively. Mostly Used region is id IR Region that is further divided into functional group region 4000-1600cm-1 and finger print region 1500-650cm-1. IR region tell us about the O-H, N-H, C-H starching in 3700-2700cm-1 and C=C, C≡C in 2700-200cm1

C=O at 1700 cm-1. In addition, most important peak C-M in range of 585-413 cm-1 is change

according to nature of metal.

19

Experiment No. 4 Preparation of Tris-thiourea copper sulphate and determination of yield. 4.1

Principle:It is the synthesis type of reaction in which Analysis is taken out gravimetrically.

Weighing out the precipitates of resulting product. It is quantitative type of Analysis in which yield is being determined of complex that is formed through coordination between donor and receptor.

4.2

Theory:This reaction is based upon complexometric reaction between metal and ligand.

Ligand has binding sites with it while metal has co-ordination number from 2-6.Some heavy transition metals have transition number 8-12. Ligand attached to metal atom and satisfies its co-ordination number. These ligands are classified as bidentate, tri, tetra and hexadentate depending upon their binding sites.

4.3

Chemicals & Apparatus:CuSO4.5H2O Thiourea, 1M H2SO4 Conical flask, Beaker, Stirrer, Filter Paper, Hirsch Funnel, Watch glass, Glass Rod

4.4

Chemical equation:s 2CuSO4.5H2O+7NH2

C

NH2

[Cu(thiourea)3]2SO4.H2O

20

4.5

Procedure:Prepared the solution of thiourea and copper sulphate. Added slowly the 15ml

solution of copper sulphate in 15 ml solution of thiourea with continuous stirring. Allowed the solution to stand. Prepared a cold solution of 10ml thiourea and added to the reaction mixture. Stirred vigorously and allowed to stand and filtered white crystals on Hirsch funnel. Recrystallized the product with dissolving in thiourea solution 0.15g in 30ml of water containing a few drops of H2SO4. Heated for 75°C to dissolve. Cooled solution filtered crystals. Washed with 5ml of alcohol. Weighed the product and determined the yield.

4.6 complex yield Calculations:Table 4.1 Theoretical Yield (g)

Actual Yield (g)

% Yield

3.60

2.4

66

%age yield = actual yield/theoretical yield × 100

4.7

Properties of ligand:Table 4.2 Molecular formula

CH4N2S

Formula mass

76.12 gmol-1

Density

1.045 gcm-3

Melting point

162 °C

21

= 2.4/3.60×100= 66 %

4.8

Solubility:Table 4.3 S.

Solvent

Solubility

1.

Water

Soluble

2.

Methanol

Sparingly

No

Soluble

3.

Ethanol

Sparingly Soluble

4.

Acetone

Sparingly Soluble

The procedure was followed C=S, ligand and Cr Salt allowed to react with but it was unsuccessful complexation does not occurred. Basic need of Complexation is symmetry of metal and ligand must match with each other. Melting point was taken the Ligand melting point is 162◦C and the product has M.P is 172◦C that show that no complex is formed. Reason for complexation is might be No optimum condition was provided, heating temperature and might be the Ligand is impure due to which the product was not obtained.

4.10

Discussion:This synthesis was gravimetric type of analysis. The product is recrystallized by

dissolving it in thiourea solution with few drops of sulphuric acid. After calculations we interpret the spectra of the complex e.g. NMR, IR UV spectra etc. shows that only thiourea is present in solution no complex is formed. Reason for complexation is might be No optimum condition was provided, heating Temperature and might be the Ligand is impure due to which the product was not obtained.

22

23

Synthesis of Schiff Base and its Tin(II) Complex A Schiff base, named after Hugo Schiff, is a compound with a functional group that contains a carbon-nitrogen double bond with the nitrogen atom connected to an aryl or alkyl group. The electrophilic carbon atoms of aldehydes and ketones can be targets of nucleophilic attack by amines. The end result of this reaction is a compound in which the C=O double bond is replaced by a C=N double bond. This type of compound is known as an imine, or Schiff base.

H3C CH3

O

CH3

N O

N

CH3

Aldehyde or ketone C=O is replaced by C=N by the attack of nucleophilic amines. This type of compound is known as imine or Schiff base.

3-D structure:-

H

H H

H

H

H H

N

N

HH

H H O

O H

H

HH

H

H

H

H

24

H

Experiment No. 5 Preparation of Ligand C12H20N2O2

5.1

Principle:The electrophilic carbon atoms of aldehydes and ketones can be targets of

nucleophilic attack by amines. The end result of this reaction is a compound in which the C=O double bond is replaced by a C=N double bond. This type of compound is known as an imine, or Schiff base.

5.2

Chemicals:Ethylenediamine, Absolute ethanol (25 mL), Acetylacetone (0.2 mol), Stannous chloride (1.9 g)

5.3

Apparatus:Flasks, Beakers, Magnetic stirrer, Funnel, Tripod stand, Filter paper

5.4

Chemical Equation:-

C2H8N2 + 2C5H8O2

→ 25

C12H20N2O2

+2H2O

5.5

Procedure:A solution of 6.68mL (0.1M) of ethylenediamine in 50mL of absolute ethanol was

slowly added drop wise to a solution of 20.5mL (0.2M) of acetyl acetone in 150mL of Absolute ethanol over a period of 2hrs. The reaction mixture was stirred for additional 1hr and filtered. The cream coloured crystals of ligand were washed with water and then with ethyl ether and dried. H3C

H3C

CH3 C

NH2

C

H2C

N

C

H2C

H2C H2C

CH2 C

C

NH2

N

O

O

O

C

O H3C

H3C

CH3

C12H20N2O2 C2H8N2 Exact Mass: 224.15 Exact Mass: 60.07 Mol. Wt.: 224.3 C5H8O2 Mol. Wt.: 60.1 m/e: 224.15 (100.0%), 225.16 (13.3%), 226.16 Exact Mass: 100.05 m/e: 60.07 (100.0%), 61.07 (1.2%) Mol. Wt.: 100.12 (2.9%) C, 64.26; H, 8.99; N, 12.49; O, 14.27 m/e: 100.05 (100.0%), 101.06 (5.6%) C, 39.97; H, 13.42; N, 46.61 C, 59.98; H, 8.05; O, 31.96

5.6

Proton NMR:-

3

2 PPM

26

1

0

5.7 C-NMR:-

220

5.8

200

180

160

140

120 100 PPM

80

60

40

20

0

Discussion:Faced some problem while performing this experiment. When added the solution of

ethylenediamine to the solution of acetyl acetone and remained it on stirring plate for about 23 hours. The cream colour ppt. were obtained but disappeared. Tried to gets stable ppts.by changing the concentration of described chemicals but the result was the same. Performed experiment two time but the result was same. Might be some impurities are present due to which the compound are ppt are formed and dissolved or might be due to less concentration of ligand.

27

Experiment NO. 6 Synthesis of Tin(II) Complex with Schiff Base 6.1

Principle:It is the synthesis type of reaction in which Analysis is taken out gravimetrically.

Weighing out the precipitates of resulting product. It is quantitative type of Analysis in which yield is being determined of complex that is formed through coordination between donor and receptor.

6.2

Theory:This reaction is based upon complexometric reaction between metal and ligand.

Ligand has binding sites with it while metal has co-ordination number from 2-6.Some heavy transition metals have transition number 8-12. Ligand attached to metal atom and satisfies its co-ordination number. These ligands are classified as bidentate, tri, tetra and hexadentate depending upon their binding sites.

6.3

Chemicals:Absolute ethanol (25 mL), Acetylacetone (0.2 mol), Stannous chloride (1.9 g)

6.4

Apparatus:Flasks, Beakers, Magnetic stirrer, Funnel, Tripod stand, Filter paper

28

6.5

Chemical Equation:SnCl4 + C12H20N2O2→ C12H16N2O2Sn +4HCl

6.6

Procedure:-

SnCl4 solution is allowed to react with Ligand but due to some reasons ligand is not formed so were not able to continue this experiment.

29

30

Experiment NO. 7

Preparation of Cis-dichlorobis(1, 2-diaminoethane) chromium(III) chloride, Cis-[CrCl2(en)2]Cl.1.5H2O 7.1

Principle:Preparation of this complex is based on the reaction between the stoichiometric

amount of the diamine and a solution of green chromium(III) chloride and dimethyl sulfoxide or dimethylforamide from which water has been distilled off. The compounds are characterized their absorption and secular dichroism spectra.

7.2

Theory:This reaction is based upon complexometric reaction between metal and ligand.

Ligand has binding sites with it while metal has co-ordination number from 2-6.some heavy transition metals have transition number 8-12. Ligand attached to metal atom and satisfies its co-ordination number. These ligands are classified as bidentate, tri, tetra and hexadentate depending upon their binding sites.

7.3

Chemicals & Apparatus:Dimethylforamide (30cm3), Chromium Chloride, 1, 2-diaminoethane (5cm3), Methanol Beaker (250cm3), Hot Plate, Dropper, Dry Pump, Filter paper, Funnel, tripod Stand

7.4

Chemical Equation:CrCl3.6H2O+2en → [Cr(en)2Cl2]Cl.H2O + 5H2O

31

7.5

Procedure:Chromium chloride is dissolved in 30 cm3 dimethylforamide in a 250cm3 beaker.

Heated it on a plate and volume is reduced to half. Now we added 5cm3 1,2 diaminoethane slowly by using a dropper. Solid purple precipitate are formed which are precipitated out by the use of methanol. The precipitates are dried at the pump. Melting point and %age yield is find out.

7.6

Yield of complex Calculations: Table 7.1 Theoretical Yield (g)

Actual Yield (g)

% Yield

2.21

1.20

54.29

% yield = actual yield/theoretical yield × 100

= 1.20/2.21× 100= 54.29%

Hence the %age yield is 54.29%

Safety Reminder: 1, 2-diaminoethane will burn the skin, Vapour Harmful. So, it should be used with care otherwise it will be harmful. .

7.7

Solubility:Table 7.2 S.

Solvent

Solubility

1.

Water

Soluble

2.

Methanol

Insoluble

3.

Ethanol

Insoluble

No

32

7.7.1 Colour:

The anhydrous compound with the formula CrCl3 is a violet solid.



The most common form of the trichloride is the dark green "hexahydrate", CrCl3.6H2O.

7.8

Properties of ligand:Table 7.3 Molecular formula

C2H8N2 60.10 gmol-1

Formula mass

0.90 gcm-3

Density Melting point

8 C0

Boiling point

116 C0

Odour

Ammonical

7.8.1 Structure:-

CH2 NH

H2C

H N

HN

CH2

Cl H2O

Cr Cl

HN CH2

Cl

C5H17Cl3CrN4O Exact Mass: 305.99 Mol. Wt.: 307.57 m/e: 305.99 (100.0%), 307.98 (91.5%), 309.98 (32.2%), 306.99 (16.5%), 308.98 (11.8%), 308.99 (5.4%), 310.98 (5.4%), 307.99 (5.2%), 303.99 (4.9%), 311.98 (4.2%), 306.98 (1.4%) C, 19.53; H, 5.57; Cl, 34.58; Cr, 16.91; N, 18.22; O, 5.20

33

7.9

Interpretation of Spectra:The interpretation of different spectra e.g.UV,IR,NMR etc are discussed here

8.9.1 IR spectra:

The IR spectrum range is from 450 – 3800 cm-1. In the IR spectra of chloro complexes, bands corresponding to ν(M–Cl) are observed at 345– 320 cm-1 indicating the pres ence of an M–Cl bond. The presence of bands at 1420–1415, 1320–1280, and 1051–1018 cm-1, in the IR spectra of the nitrato complexes suggests that both nitrate groups are coordinated to the central metal ion in a unidentate manner

7.9.2 Proton NMR:

2

PPM

1

0

Carbon atom is attached with Nitrogen which is more electronegative. So the peak will be downfield. It shows two peaks one at 2ppm and other is at 2.90ppm.

34

7.9.3 Carbon NMR:

25

20

15 PPM

10

5

0

The carbon NMR of Tris (1,2 diaminoethane) chromium(III) complex shows only one peak at 27ppm. 7.9.4 UV spectra:

Table 7.4 Complex

λmax (nm)

Cis-[CrCl2(en)2]Cl.1.5H2O

364

Interpretation of UV-Visible spectra:For UV-visible 0.001M solutions were prepared and spectra were taken. The Cis-[CrCl2(en)2]Cl.1.5H2O Complex show Maximum Absorbance at 364nm.the transition metal in the complex has empty d orbital upon the absorbance of light in the range of visible light the lower laying electron in t2g is move toward eg orbital at higher energy so the transition of electron from t2g to eg called d-d transition due to which the compound show the colours.

35

7.10

Discussion:It was complexometric reaction between metal and ligand reacts with each other.

After precipitate is formed need to a pump to dry them but unfortunately it was not available, but managed the things by dying them in sunlight. After drying performed the calculations and wrote the results. The solubility e.g.in water, ethanol chloroform etc. was checked .Interpretation of different spectra was a bit tough as we have not instruments like IR,NMR and X-Ray Diffraction. So, collected data from online sources. Properties and structure are also being explained at the last we have different applications of the described metal and complexes which are discussed in detail. For UV-Visible studies 0.001M solutions were prepared and spectra were studied that give the Lambda max value at 364nm the range of UV-visible is 180-800nm. The Complex shows Maximum Absorbance at 364nm. The transition metal in the complex has empty d orbital upon the absorbance of light in the range of visible light the lower laying electron in t2g is move toward eg orbital at higher energy so the transition of electron from t2g to eg called d-d transition due to which the compound show the colours.

The NMR spectra of both complex and Ligand was taken both are the different from each other giving the different peaks of proton and C at different value of Chemical shift that indicates the formation of the complex between the Transition metal and Ligand.

IR spectra of complex gives the different information about the complex. The IR range is from 12500cm-1 to 10cm-1. It is divided into three regions, Near IR region, Mid IR region, Far IR Region having range 12500-4000cm-1, 4000-200cm-1 and 200-10cm-1 respectively. Mostly Used region is id IR Region that is further divided into functional group region 4000-1600cm-1 and finger print region 1500-650cm-1. IR region tell us about the O-H, N-H, C-H starching in 3700-2700cm-1 and C=C, C≡C in 2700-200cm-1C=O at 1700 cm-1. And most important peak C-M in range of 585-413 cm-1 is change according to nature of metal.

36

IR Ranges for Respective Complex:-

C-N stretching

1500-1300cm-1

C-C stretching

1300-800 cm-1

Cr-N stretching

585-413 cm-1

Cr-Cl Starching

579-354 cm-1

37

Experiment NO. 8 Preparation of Cis k-⌠Cr(OX)2(H2O)2⌡.H2O 8.1 Principle:It is based on the reaction between the stoichiometric amount of the potassium dichromate and oxalic acid dihydrated. The compounds are characterized their absorption and circular dichroism spectra.

8.2 Theory:It is based upon complexometric reaction between metal and ligand. Metal has coordination number may be 2-6 but some heavy transition metals have coordination 812.Lignad attached to metal atom and satisfies its co-ordination number. These ligands are classified as bidentate, tri, tetra and hexadentate depending upon their binding sites.

8.3 Chemical & Apparatus:Ground potassium dichromate, Oxalic acid dihydrated, Water (one-two drop), Ethanol China dish, watch glass, dropper, stirrer, glass rod, filter paper, dry at pump

8.4 Chemical Equation:-

K2Cr2O7 + (COOH)2 → Cis k-⌠Cr(OX)2(H2O)2⌡.H20

38

8.5 Procedure:Prepared a mixture of finely ground potassium dichromate and oxalic acid dehydrate heap mixture in dish. Place one drop of water and cover with watch glass. After short induction period the reaction commences and soon become vigorous. The product of this reaction is purple viscous liquid. Over which poured ethanol, mixture is stirred and ground with glass rod, repeat process with second portion of ethanol. Filter, dry at pump and determine yield.

8.6

Yield of complex Calculations: Table 8.1 Theoretical Yield (g)

Actual Yield (g)

% Yield

12

6.46

53

% yield=

8.7

actual yield/theoretical yield × 100

= 6.46/12×100= 53%

Solubility:Table 8.2 S.

Solvent

Solubility

1.

Water

Soluble

2.

Methanol

Insoluble

3.

Ethanol

Insoluble

4.

Chloroform

Soluble

No

39

8.8 Properties of ligand:Table 8.3 Molecular formula

C2H2O4 90.03 gmol-1

Formula mass Density

1.90 gcm-3

Melting point

102 to 103

Odour

8.8.1

Carbolic odour

Structure: OH

HO O

Cr

O

C

O C

K

O

O

H2O

O

C

C

O

O

The complex of chromium with oxalate ions is fairly easy to form. A great care is required while pouring the mixture on watch glass and making it somehow wet with only one drop of water otherwise a severe reaction will takes place.

8.9

Interpretation of Spectra:The interpretation of different spectra e.g. UV, IR, NMR etc. are discussed here

8.9.1 IR spectra:The IR spectrum for this complex show bands in the 3,600–3,200 cm-1 region correspond to stretching vibrations. Moreover, the broad band in the range 3,300–3,100 cm-1, observed also in the oxalic acid dihydrated, can be assigned to strong hydrogen bonds. ν (OH) and ν (O-H) of water molecules. The Concerning the oxalate groups, the vibration frequencies appearing between 1,700 and 1,000 cm-1 confirm their various coordination modes via one to four oxygen atoms. The two spectra give also characteristic vibrations of

40

oxalate ligands, localized at 1,690, 1,470, 1,400, 1,250 cm-1. In the high frequency range, the broad band centered at 3,500 cm-1 can be assigned to H-bonded hydrogen oxalate groups vibrations. More interesting are the peaks in the region 1,730–1,000 cm-.The bands at 1,720 and 1,710 cm-1 are attributed to C=O stretching of COOH group and the peaks at 1,630 ,,470 and 1,410 as well as those at 1,286 and 1,220

(C-O),1,110 (C-OH) and 722 cm-support

the presence of bridging-chelating oxalate group observed near 590 cm-1.

8.9.2 Proton NMR:

2

1

PPM

0

This K[Cr(OX)2(H2O)2].H2O complex show broad peak due to impurities. Water molecule outside the sphere does not show any absorbance.

8.9.3 Carbon NMR:-

160

140

120

100

PPM

80

60

40

20

0

This complex shows only one peak in Carbon NMR. It shows peak at 160ppm. Carbon will be attracted towards the Oxygen because of its higher electronegativity. So the peak will be down field.

41

UV Spectrum:-

1.5

Sm ooth: 25

ABS

Deri.: 0

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

nm 200

250

300

350

400

450

500

550

600

650

700

750

800

UV-Visible spectrum in the range 250–800 nm. The peak is maximum at about 260 nm.

Table 8.4 Complex

λmax (nm)

Cis k-⌠Cr(OX)2(H2O)2⌡.H2O

260

Interpretation of UV-Visible spectra:For UV-visible 0.001M solutions were prepared and spectra were taken. The Cis k-⌠Cr(OX)2(H2O)2⌡.H2O Complex show Maximum Absorbance at 260nm.the transition metal in the complex has empty d orbital upon the absorbance of light in the range of visible light the lower laying electron in t2g is move toward eg orbital at higher energy so the transition of electron from t2g to eg called d-d transition due to which the compound show the colours.

42

8.10 Discussion:For this oxalate bidentate ligand was used to form complex. The synthesis involves the redox reaction in which oxalate serve as reductant oxalate function as ligand. The purpose of these experiments to prepare Cr-Complex with ligands. Ligands used was oxalate, ethylenediamine, and thiourea etc. Cr is transition metal having colured complexes with different ligands.it has d-orbitals that are degenerate and 5 in number. The name of the element chromium is derived from the Greek word, Chroma, meaning colour, because many of its compounds are intensely coloured. Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6. It has unfilled d orbitals in no 5 dxy dyz dzx dx2-y2 dz2. eg ↑

↑

↑ ↑

t2g↑

↑

5 dxy dyz dzx dx2-y2 dz2

The chromium Complex shows Absorbance at lambda nm. The transition metal in the complex has empty d orbital upon the absorbance of light in the range of visible light the lower laying electron in t2g is move toward eg orbital at higher energy so the transition of electron from t2g to eg called d-d transition due to which the compound show the colours.

43

Experiment No. 9 Preparation of Tris (1,2-diaminoethane) chromium(III) chloride. 9.1 Principle:It is based on the reaction between the stoichiometric amount of the Chromium sulphate and Ethylenediamine from which water has been distilled off. The compounds are characterized their absorption and secular dichroism spectra.

9.2 Theory:This reaction is based upon complexometric reaction between metal and ligand. Ligand has binding sites with it while metal has co-ordination number from 2-6.some heavy transition metals have transition number 8-12. Ligand attached to metal atom and satisfies its co-ordination number. These ligands are classified as bidentate, tri, tetra and hexadentate depending upon their binding sites.

9.3 Chemicals & Apparatus:Chromium sulphate (25 g), Ethylenediamine 99%, Hydrochloric acid. Conical flask, Sprit lamp, Air condenser, Beaker, Stirrer, Filter Paper.

9.4 Chemical equation:CrSO4 +3en 9.5

[Cr(en)3]2(SO4)3

Procedure:The first stage in this synthesis is the preparation of Tris ethylenediamine chromium

sulphate from which the chloride is obtained by the treatment with HCl. Placed 25g chromium sulphate at 1000c and ethylenediamine is added. Fit the flask on air condenser and heat on steam bath. The chromium sulphate is soon begun to lose its colour. A brown mass is finely produced which is left on the steam bath for 12 hour. Grind the product to powder form. Washed with alcohol and dry in air.

44

9.6 Observations:After mixing up the solution needed steam bath to put our product on it. But unfortunately steam bath was not available so used water bath instead of it. The temperature of water can rise only up to 100 C0 and needed higher temperature so this trick didn’t work. So, after being consulted with the instructor he told to use the burner and placed beaker on it directly. Kept solution on the burner for about 6-8 hours but unluckily nothing happened in the favour of desired results. So due to unavailability of steam bath the results are not obtained of this experiment.

9.6 Reason:Complexation did not occurre due to unavailability of optimum conditions for complexation. Might be some impurities were present due to which complex is not formed. There was also a main reason of unavailability of steam bath due to which desired results could not be achieved. For complexation the geometry of ligand and metal should be same if not complex did not form.

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