By- Mr.Dinkar Kamkhede

M.Sc CHE 2014

Coordination chemistry is the branch of chemistry, which lets us know how

metal complexes are built. A complex is a cluster of ions and molecules, which

can exists independently but prefers to join together in a structurally well

defined manner. A metal complex consists of a metal ion, often structurally

well-defined manner. A metal complex consists of a metal ion, often referred to

as the central metal atom or ion, which binds a number of ions and or

molecules, called ligand.

The reorganization of true nature of complexes began with

Alfred Warner, who in 1893 proposed what is now commonly referred to as

Warner’s coordination theory He prepared an characterized hundreds of

coordination compounds. For this major contribution, Warner awarded the

noble prize in chemistry in 1913.

The interaction of transition metal ions with biological molecules provides one of

the fascinating areas of coordination chemistry.

The application has been grown readily due to their wide range in household,

industry, medicine, chemical and biological system. Some of the important once

are

Plant growth:

Plants need various nutrients for healthy growth. Essential nutrients

include number of mental such as iron, copper and zinc etc. Iron in the +3 state

the soil is mostly hydrolyzed to from insoluble iron hydroxide, which cannot be

taken up by plants. Deficient in iron are likely to develop a disorder known as

iron chlorosis, evidenced by yellowing leaves.

• Therapeutic chelating agents:

The coordination complex of platinum effectively inhibit the growth of cancerous cells.

It has long been suspected that chelation processes are associated both with the

development of cancer and with antitumor actively

Important of cefadroxil

Cefadroxil is a broad – spectrum antibiotic of the cephalic sporum HPE Effectixe in

gram positive and gram negative bacterial infection. It is a bactericidal

antibiotic.Cefadroxil is a first generation cephalosporin antibacterial ative of cefadraxil.It

has been effectiom of the skin and urinary fract.

Pharmacakinetics:-cefadroxil is almost completely absorded from gastrointestinal

tract after does of 500 mg and 19 by mouth, peak plasma doncetration of about 16 and

30 micrograms/ ml are bastioned after 1.5 to 2 hours.

It is widely distributed to body tissue and fluid it crosses the placentas and appears in

breast milk.

Side effect :- toast common side effect cefadroxil is diarrhea, nausea,

upset stomach and vomiting other rahshes hixes, itching .

Dental use :- is used as antibiotic prophylaxis dental pracedare fpr patiens

allergic to penicillin.

Veterinary use :- Canbe used for treating interacted woinds on animals

usuallyin powder from mixied with water has a colorand smell similar amount

dependent on their we igth and severity of intercting.

General Methods to Study Metal Complexes:

The numbers of methods deal with the study of metal –ligand complexes in

solution are

,

pH Metric Technique-

Metal complex formation may be taken place due to the displacement of

proton from ligand causing a drop in the pH- metric value of the solution. Irving and Rossotti

61 have given a method for calculation of stability constants of complexes by pH-metric

technique. This general technique has been followed by Calvin and bjerrum.

Co-relation between the basicity of the ligand and stability of complexes: The complex formation is a complexation between metal ions and protons in

most cases. Therefore, it is reasonable to expect that there is some correlation between the

stability constant of the complex and the acidic dissociation constant of conjugate acid of the

ligand.Larsson" finds linear relationships between the corresponding constants for the

complexes of silver ion with organic amines. Subsequently similar correlations were found in

many complex systems". The ligand may affect the chelating tendency in two possible ways.

•It may influence of basicity of donor group by inductive and resonance effect.

•The addition of groups on the ligand may be purely statistical. Sterical effects prevent the

ligand ions or molecules from acquiring the orientation about the central metal ion most

favourable for chelation.

Determination of the stability constants from the experimental data consist

of three steps:-

The determination of the formation curve of the system expressed as a Plot

•The calculation of values of log K1 and log 2 by solving the formation

of the system.

n-n-n-

-------------- (16)against log K = log 1

[L]

•The calculation of values of log K1 and log K2 by solving the formation

of the system.

• The conversion of stoichiomctric constants into the thermodynamic

functions

The experimental procedure involves titration of:

•Nitric Acid (A)

•Nitric Acid -1- Ligand Acid (A + L)

•Nitric Acid * Ligand Acid + Metal Salt (A — L + hi)

With standard solution of sodium hydroxide. The ionic strength of each

solution is kept constant at 0.01 M by addition of 1.00 potassium nitrate

solution

Calculation of A, n and pL

n-

A= y -

(V2 - V1) (N + E0)

(V0+ V1 ) T

0 L

1)The experimental data obtained from the titration curves helps in calculation of nA n

and pL.i) Proton ligand formation number nA for different pH values can be obtained from

expression.

2)The metal ligand formation number n can be calculated from the expression:-

=

Chapter – III

EXPERIMENTAL, RESULTS AND DISCUSSION

ExperimentalSolvents

Distilled Water:

Distilled water prepared may contain small quantities of dissolved ammonia and carbon

dioxide.Distilled water used investigation was obtained by redistilling twice the distilled water

prepared from alkaline potassium permanganate: the head and tail fractions were rejected to

remove the dissolved ammonia'`. The dissolution of carbondioxide was prevented during

distillation by connecting a potassium hydroxide trap in the receiver of distillate. The resulting

distillate was boiled to expel oxygen and then it was cooled in a well-stoppered glass bottle

(Distilled water free from ammonia and carbondioxide had pH 7.00)

Sodium Hydroxide:

The solution of sodium hydroxide {E. Merck} was prepared carbonate by allowing the

solution to stand for along time till any if present precipitated. The solution was filtered

through a sintered glass crucible and kept in a pyrex veasel free from carbondioxide and

was used as the titrant for the pH-metric titrations. Titrating against standard oxalic acid

solution before starting an experiment standardized the solution of sodium hydroxid.

Formation Curves –

The formation curves were constructed by plotting the values of

Aagainst pH of solution and are presented in Fig. 19 to 34. The dissociation constant pk of

ligands are calculated from formation curves. The values of pk obtained are represented in Table

34(a). The dissociation constants (pk values) for substituted ligands are found to be above pH

10.00 for all the systems.

Meta I-Ligand Stability Constants –

The metal Ligand stability constant is the association or formation constant. For the conversion of

any Calvin-Bjerrum titrations data -into stability constants, following conditions should hold

good for the system under investigation.

•Formation of complex or chelate under the experimental conditions Employed.

•Absence of metal ion hydrolysis, polynuclear hydrogen and hydroxyl complexes and anion of

complexing metal ions.

System log log

Cu (II) ligand 1.29 0.386

Metal-Ligand stability constant

Conclusion

•The departure between acid curve and ligand curve indicated the dissociation of phenolic. -OH

group.

•The departure between ligand curve and metal curve indicated the commencement of complex

formation.

•The change in colour during pH-metric titration also indicated the fomution of complexes

between ligands and metal ions.

The values of pK and log K arc increased with increasing the mixture of water which is attributed

due to the effect of bulky solvent.

•The non-linear relationship for the graphs I:D versus pK/log K but linear relation

relationship for the graphs between mole fraction versus pK/log K is observed.

Volume of Alkali added Titration free acid Titration of free acid + Ligand Titration of free acid +ligand + Metal

Cu II

0.00 1.5 1.5 1.5

0.5 1.7 1.7 1.7

1.0 1.9 1.9 1.9

1.5 2.1 2.1 2.1

2 2.1 2.1 2.1

2.5 2.3 2.3 2.3

3 2.5 2.5 2.5

3.5 3 3 3

4 3.5 4 3.7

4.5 4.6 4.7 4.3

5 5.4 5.5 4.7

5.5 6.3 6.4 5.3

6 7.5 7.3 5.8

6.5 8.7 8.2 6.7

Table 1: pH – Metric Titration Data

0

2

4

6

8

10

12

14

1 2 3 4 5 6 7 8 9 10 11 12

pH

Volume of NaOH

Ligand

Metal

Table2: Determination of A Values

pH V1(ml) V2 (ml) V2 - (ml) A

4 4.8 4.90 0.10 0.8087

4.5 4.9 5.00 0.10 0.8087

5 5.10 5.20 0.10 0.8094

5.5 5.5 5.70 0.20 0.6216

6 5.80 6.00 0.20 0.6236

6.5 6.00 6.20 0.20 0.625

7 6.20 6.45 0.25 0.477

7.5 6.19 7.20 0.25 0.539

8 7.45 7.70 0.25 0.542

8.5 7.45 7.75 0.30 0.451

9 7.65 8.30 0.30 0.099

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1 2 3,5 4 4,5 5 5,5 6 6,5 7 7,5 8 8,5 9 9,5

pH

pH V2(ml) V3 (ml) V3 – V2 (ml)

4 4 3.7 0.3 2.91

4.5 4.7 4.3 0.4 8.83

5 5.5 4.7 0.8 7.56

5.5 6.4 5.3 1.1 10.2

6 7.3 5.8 1.5 13.74

6.5 8.2 6.7 1.6 14.52

7 9.2 7.6 1.6 14.98

7.5 10 8.3 1.7 17.60

8 10.2 8.4 1.8 16.83

8.5 10.4 8.5 1.9 16.68

9 10.7 8.7 2.0 17.90

9.5 11.1 9.00 2.1 18.04

10 11.8 10.1

Table2: Determination of

0

0,5

1

1,5

2

2,5

3

3,5

4

4,5

1 2 3 3,5 4 4,5 5 5,5 6 6,5 7 7,5 8 8,5 9 9,5pH

n

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