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As we know, Manganese is found in the first row of transition metal with the electron configuration [Ar] 3d5 4s2. Besides that, Manganese has different type of oxidation states when it appears as a compound and the oxidation state is from Mn(-III) until Mn(VII). So, we know that the compounds of manganese range in the oxidation number have a different of 10 electrons. In the experiment 1, we prepare tris(acetylacetonato)manganese(III), Mn(acac)3 by using manganese(II) chloride tetrahydrate and potassium permanganate act as oxidation agent to oxidise manganese(II) chloride to acetylacetonemanganese(III).

Manganese(III) acetylacetonate is an one- electron oxidant. Manganese(III) acetylacetonate

is high spin. It has also a distorted octahedral structure. This distortion is due to the Jahn-Teller effect. (Absolute Astronomy, 2009). The structure of Manganese(III) acetylacetonate is shown as below:-

(Source: Tcieurope.com)

The equation is as follow:-

MnCl2 + 4H2O Mn(H2O)4Cl2

Mn(H2O)4] Cl + 2HC5H7O2 + NaC2H3O2 Mn(C5H7O2)2 + NaCl + HC2H2O2

4Mn(C5H7O2)2 + KMnO4 + 7HC5H7O2 + HC2H3O2 5Mn(C5H7O2)3 + KC2H3O2 + 4H2O

Furthermore, bis(acetylacetonato)oxovanadium(IV) is also known as Vanadyl acetylacetonate, VO(acac)2. As we know, it is a blue green complex. bis(acetylacetonato)oxovanadium(IV) has a vanadyl group, VO2+. The vanadyl group is bonded to 2 acetylacetonate anions and the structure of the compound is as follow:-

This complex can be made from vanadium(IV) or vanadium(V). In our experiment, bis(acetylacetonato)oxovanadium(IV) was prepared from vanadium(V) oxide and the equation is as follow:-

V2O5 + 2H2SO4 + EtOH 2VOSO4 + 3H2O + CH3CHO

VOSO4 + 2HC5H7O2 + Na2CO3 VO(C5H7O2)2 + Na2So4 + H2O + CO2

(Absolute Astronomy, 2009)

Besides that, both of the acetylacetonato (acac) groups of bis(acetylacetonato)oxovanadium(IV) are able to be exchanged with organic ligands having coordinating atoms of different potentialities. (Maurya, 2003)

Both Manganese(III) acetylacetonate and bis(acetylacetonato)oxovanadium(IV) are bond with acetylacetonate which known as ligand. The precursor for acetylacetonate is acetylacetone with formula C­5H8O2. However, acetylacetonate is an anion. It can bind to corresponding cation but it very hard to exist as a free ion in solution.

In addition, Cobalt is a hard, gray metal. It has a proton number 27. Besided that, there are two types of cobalt ions namely Co2+ and Co3+. First, Co3+ ion is more weaker than the Co2+ ion. However, the complex ion formed with higher oxidation state is more stable. ( °zmir Institute of Technology, n.d.). So that, Cobalt(III) complexes are kinetically inert.

Co3+ can undergo a process known as ligand exchange reactions slowly which compared to Co2+ complexes. The cobalt(III) complexes are usually in octahedral shape. In the experiment, chloropentaamminecobalt(III) chloride is being synthesized. The structure is as follow:-

(Source: Chemicalbook.com)

The complex is prepared by the oxidation of ammoniacal solution of cobalt(II) salts by using hydrogen peroxide. The formula is as follow:-

Co2+ + NH4+ + 1/2H202 → [Co(NH3)5H20]3+

[Co(NH3)5H20]3+ + 3Cl- → [Co(NH3)5Cl]Cl2 + H20

( °zmir Institute of Technology, n.d.)

Materials and Methods :

Experiment one

5g of MnCl2.4H20

1.3g of NaC2H3O2.3H2O NaC2H3O2.3H2O

Dissolved in 200cm3 of distilled water.

21cm3 of 2HC5H7O2 slowly added

1g of KMnO4

Present of two-phase layer

Solution A added in with stirring

Dissolved in 50cm3 of distilled water.

13g of NaC2H3O2.3H2O

Solution B added in

Solution A

Solution B

Dissolved in 50cm3 of distilled water.

Heated with 60oC for 30 minutes

Complex washed with acetone

Solid complex filtered by suction

Resultant solution was cooled with ice-cold water

Experiment 2

Experiment 3

Recrystallise

Results :

For experiment 1,

from the equation below, I can get the theoretical mass of the Mn(acac)3 solid complex by :

Mn(H2O)4] Cl + 2HC5H7O2 + NaC2H3O2 Mn(C5H7O2)2 + NaCl + HC2H2O2

4Mn(C5H7O2)2 + KMnO4 + 7HC5H7O2 + HC2H3O2 5Mn(C5H7O2)3 + KC2H3O2 + 4H2O

From the equation, we know that 1 mol of Mn(H2O)4] Cl = 1 mol of Mn(C5H7O2)2.

So, 5 g of Mn(H2O)4] Cl = 0.0308 mol is also = 0.0308 mol of Mn(C5H7O2)2.

From the second equation, 4 mol of Mn(C5H7O2)2 = 5 mol of Mn(acac)3

0.0308 mol of Mn(C5H7O2)2 = 0.0385 mol. Of Mn(acac)3

So, theoretical weight of Mn(acac)3 = 0.0385 mol X 252.938 g/mol

theoretical weight of Mn(acac)3 = 9.7381 g

The following shows the method to get our experimental weight:

Weight of Sample tube

14. 8180 g

Weight of Sample tube + solid complex , Mn(acac)3

18.7785 g

So, the experimental weight of Mn(acac)3complexes were 3.9605 g

Percentage yield of Mn(acac)3complexes we get was = 3.9605 g / 9.7381 g X 100 %

= 40.67 %

Next, Magnetic moment of Mn(acac)3complexes were calculated as follow :

m = 0.9278g- 0.8193g

= 0.1085g

Ro= -33

L = 2.4cm

R= 1165 (paramagnetic)

CBal = 1

X(g) = [CBal X L X (R-Ro) ] / 109 X m

X(g) of Mn(acac)3complexes = 2.65 X 10-5

So, Mn(acac)3complexes are paramagnetic

FTIR

Interpretation of IR spectrum for complexes will be written in discussion.

For experiment 2,

from the equation below, I can get the theoretical mass of the [Co(NH3)5Cl]Cl2 solid complex by :

Co2+ + NH4+ + 1/2H202 → [Co(NH3)5H20]3+

[Co(NH3)5H20]3+ + 3Cl- → [Co(NH3)5Cl]Cl2 + H20

From the above equation, 1 mol of Co2+ = 1 mol of [Co(NH3)5H2O]3+

12g of Co2+ = 0.0504 mol

So 0.0504 mol of [Co(NH3)5H20]3+= 0.0504 mol of [Co(NH3)5Cl]Cl2

Theoretical weight of [Co(NH3)5Cl]Cl2 solid complexes = 0.0504 mol X 250.433 g/mol

= 12.6218 g

The following shows the method to get our experimental weight:

Weight of Sample tube

14. 9285 g

Weight of Sample tube + solid complex ,

22.3723 g

So, the experimental weight of [Co(NH3)5Cl]Cl2 solid complexes = 7.4438 g

Percentage yield of [Co(NH3)5Cl]Cl2complexes = 7.4438 g / 12.6218 g X 100 %

= 58.98 %

Next, Magnetic moment of [Co(NH3)5Cl]Cl2complexes were calculated as follow :

m = 0.9264g- 0.8207g

= 0.1057g

Ro= -36

L = 2.1cm

R= -41 (dimagnetic)

CBal = 1

X(g) = [CBal X L X (R-Ro) ] / 109 X m

X(g) of [Co(NH3)5Cl]Cl2complexes = -9.9338 X 10-8

So, [Co(NH3)5Cl]Cl2complexes are diamagnetic

FTIR

For experiment 3,

from the equation below, I can get the theoretical mass of the [Vo(acac)2(H2O)] solid complex by :

V2O5 + 2H2SO4 + EtOH 2VOSO4 + 3H2O + CH3CHO

VOSO4 + 2HC5H7O2 + Na2CO3 VO(C5H7O2)2 + Na2So4 + H2O + CO2

From the above equation, 1 mol of V2O5 = 2 mol of VOSO4

2g 0f V2O5 = 0.011 mol = 0.022 mol of VOSO4

2 mol of VOSO4 = 2 mol of VO(C5H7O2)2