PhD. Halina Falfushynska

Manganese is obtained mainly from the mineral pyrolusite, MnO2.

Ferromanganese alloys are wear resistant and shock resistant and are used for railroad tracks, bulldozers, and road scrapers.

Manganese(IV) oxide is the starting point for making most other manganese compounds.

Potassium permanganate, KMnO4, is an important oxidizing agent that is used in both analytical and organic chemistry laboratories, and in water treatment.

Iron is the fourth most abundant element in Earth’s crust. Cobalt and nickel are not nearly as common.

All three elements form 2+ and 3+ ions. The most common ions of Co and of Ni are the

2+. The most common ion of Fe is the 3+ due to the half-filled d-subshell:

The iron triad exhibits ferromagnetism which is a much stronger magnetic effect than paramagnetism.

A ferromagnetic solid consists of regions called domains in which atoms have their magnetic moments aligned.

• When placed in a magnetic field, all the domains are aligned and the solid becomes magnetized.

Examples of variable oxidation states in the transition metals

Iron

Iron has two common oxidation states (+2 and +3) in, for example, Fe2+ and Fe3+. It also has a less common +6 oxidation state in the ferrate(VI) ion, FeO4

2-.

Manganese

Manganese has a very wide range of oxidation states in its compounds. For example:

+2 in Mn2+

+3 in Mn2O3

+4 in MnO2

+6 in MnO42-

+7 in MnO4-

Thinking about a typical transition metal (iron)

Here are the changes in the electronic structure of iron to make the 2+ or the 3+ ion.

Fe [Ar] 3d64s2

Fe2+ [Ar] 3d6

Fe3+ [Ar] 3d5

The 4s orbital and the 3d orbitals have very similar energies. There isn't a huge jump in the amount of energy you need to remove the third electron compared with the first and second.

The figures for the first three ionisation energies (in kJ mol-1) for iron compared with those of calcium are:

metal 1st IE 2nd IE 3rd IE

Ca 590 1150 4940

Fe 762 1560 2960

There is an increase in ionisation energy as you take more electrons off an atom because you have the same number of protons attracting fewer electrons.

Manganese Mn (Manganum)

trace element- cofactor of enzymes: superoxide dismutase

pyruvate carboxylaseKMnO4 Potassium permanganate (INN: Kalii

permanganas)

- in water dissolves to give deep purple solutions- strong oxidizing agent- dilute solutions can act as desinfectant

Iron Fe (Ferrum)important microelementhuman body: 4–5 g Fea) functional form - heme iron proteins

hemoglobin 70 %myoglobin 5 %

some enzymes - non-heme iron proteinsb) tranport form (transferrin)c) storage of iron (ferritin, hemosiderin)-20 %Fe in food 10-30 mg/day absorption: only

7-10% ~ 1 mg/day

HEME iron proteins

Hemoglobin - O2 transport in blood

- in red blood cells- tetramer = 4 subunits

(each subunit: one heme + one globin)

HbA ("adult") 22

HbF ("fetal") 22

Myoglobin - "O2 storage" in muscle cell

Cytochromes - electron transport - their function is based on: Fe2+ (reduced)

Fe3+ (oxidized)

heme

Non-heme iron proteins FeII or FeIII bound to protein SH

iron–sulphur proteins (FeS proteins)

Transferrin - blood plasma protein ( 1 globulin )

- transport of Fe - 1 molecule of transferrin can carry 2 iron ions in

form of Fe3+

Ferritin - intracellular iron storage protein (liver, bone marrow)

- 1 ferritin complex can store about 4500 Fe3+

- ferritin without iron = apoferritin

Hemosiderin - "damaged (Fe-overloaded) ferritin" - Fe from it is less available

OVERVIEW OF IRON METABOLISM

liver FERRITIN HEMOSIDERI

N

blood plasma TRANSFERRIN

bone marrow FERRITIN

red blood cells HEMOGLOBIN

spleen FERRITIN

tissues CYTOCHROMESFe-S proteins

muscles MYOGLOBIN

BLEEDING (Fe losses)

FOOD

Iron metabolism = unique - reutilization ! (closed system)

NO regulated excretion system for Fe !

Fe absorption must be "regulated"

Loss of Fe through loss of blood (females - mestrual bleeding)

Iron deficiency - microcytic anemia "iron deficiency anemia"

Iron overload - hemochromatosis = accumulation of iron in the body

(depositions as hemosiderin)

organ dysfunction (liver, heart, ...)

IRON ABSORPTION

FOOD Fe3+

STOMACH

HCl pH 1-2ascorbic acidgastroferrin - iron binding protein

Fe2+

reduction

INTESTINAL MUCOSA CELL

Fe3+

apoferritin

ferritin (Fe3+)

BLOOD transferrin (Fe3+)

Fe2+