stk1113 group 10 - chemistry of vitamin b12

Presented by: Wong How ChuTan Shing Cheng Jacqueline Tiong Liq

Lin

Andrew Dino Anak Najib(20658 WS47)

Diyanah Musfirah bt Jamal(20873 WS47)

Jacqueline Tiong Liq Lin(21099 WS47)

Marly Matleen Anak Augustine Agoh(21412 WS47)

Nabile binti Satibi(21643 WS50)

Nur Amiza bt Matsah(21896 WS47)

Nurul Ikma binti Razali(22056 WS50)

Siti Kamilah bt Mohamed(22339 WS50)

Tan Shing Cheng(22501 WS47)

Wong How Chu(22635 WS50)

Project Manager:

Jacqueline Tiong Liq Lin

Note Taker:Siti Kamilah bt Mohamed

Explain what tetradentate and hexadentate ligands are.

Determine the shape and the coordination number for tetradentate and hexadentate

Answering questions posted by the Medical Committee

INTRODUCTIONINTRODUCTION

Vitamin B12 is a water soluble vitamin with a key role in the normal functioning of the brain and nervous system, especially the formation of blood.

It is structurally the most complicated vitamin

• Vitamin B12 is a collection of cobalt and corrin ring molecules which are defined by their particular vitamin function in the body.

Chemical structure of Vitamin B12

• Systemic IUPAC name is α-(5,6-dimethylbenzimi-dazolyl) cobomidcyanide

Porphyrin group in the structure of Vitamin B12

The diagram shows the structure of Vitamin B12 with the porphyrin group being highlighted.

In the structure of vitamin B12, it has a metal (Co) complexed to a tetradentate porphyrin group, nitrogen and a psedonucleotide.

The diagram above shows the structure of porphyrin.

LIGANDSLIGANDS

Charged or uncharged molecule, with one or more unshared pairs of electrons, that can attach to a central metallic atom or ion to form an aggregate known as a complex ion (Huheey et al., 1993)

Latin: ligare = “to bind”

In forming a complex, a ligand is said to coordinate to the metal.

Prefix Meaning

Mono- 1

Di- or Bi- 2

Tri- 3

Prefix Meaning

Tetra- 4

Penta- 5

Hexa- 6

A chelating agent which has four groups capable of attachment to a metal ion

Also known as quadridentate ligand

Has 4 lone pairs of electrons

• important for the chelation of iron on hemoglobin

• a tetradentate ligand

Hexadentate ligand is a chelating agent which has 6 groups capable of attachment to a metal ion

Also known as sexadentate ligand

Has 6 lone pairs of electrons

Ethylenediaminetetracetic acid

Used for the removal of heavy metals from animal tissues

The EDTA ion entirely wraps up a metal ion using all the 6 positions

Coordination number = 6, because 6 coordinate bonds are formed by the central metal ion

Tetradentate Hexadentate

Shape Square planarTetrahedral

OctahedralTrigonal prismatic

Coordination number

4 6

Number of lone pairs of electrons 4 6

Square planar

Tetrahedral

Octahedral

Trigonal prismatic

ANSWERS TO ANSWERS TO QUESTIONS POSTED QUESTIONS POSTED FROM THE MEDICAL FROM THE MEDICAL

COMMITTEECOMMITTEE

[Fe(C2O4)3]2-

Trioxalateferrate(III) ion

K4[Fe(CN)6]

(i) Potassium hexacyanoferrate (II)

Roman numeral represents oxidation number

(ii) Potassium hexacyanoferrate (4-) Arabic numbers represents net charge

(iii) Tetrapotassium hexacyanoferrate

(1) Leigh, G. J., ed., Nomenclature of Inorganic Chemistry (1990). IUPAC. Blackwell Scientific Publications, England. p 152 - 157.

(2) Huheey, J.E., Keiter, E.A., Keiter, R.L.(1993). Inorganic Chemistry-Principles of Structure and Reactivity. Fourth Edition. HapperCollins College Publishers, New York.

(3) Rawn, J.D., Kask, U. (1993). General Chemistry. Wm. C. Brown Communication. p 812-840.

(4) Brown, T.L., LeMay, H.E., Jr., Bursten, B.E., Murphy, C.J. (2009) Chemistry – the Central Science. Eleventh Edition. Pearson Education, Inc., New Jersey. p 1015 – 1041.

(5) Wikipedia. Vitamin B12. Retrieved on 9 Feb 2009 from http://en.wikipedia.org/wiki/Vitamin _B12

QUESTIONS?QUESTIONS?

Thank you !