Write down the IUPAC name for each of the following complexes and indicate the oxidation state,

Solution:

(i) Potassium diaquadioxalatochromate (III) trihydrate.

Oxidation state of chromium = 3

Electronic configuration: 3d3: t2g3

Coordination number = 6

Shape: octahedral

Stereochemistry:

Magnetic moment, $\mu=\sqrt{n(n+2)}$

$=\sqrt{3(3+2)}$

$=\sqrt{15}$

(ii) [Co(NH3)5Cl]Cl2

IUPAC name: Pentaamminechloridocobalt(III) chloride

Oxidation state of Co = +3

Coordination number = 6

Shape: octahedral.

Electronic configuration: d6: t2g6.

Stereochemistry:

Magnetic Moment = 0

(iii) CrCl3(py)3

IUPAC name: Trichloridotripyridinechromium (III)

Oxidation state of chromium = +3

Electronic configuration for d3 = t2g3

Coordination number = 6

Shape: octahedral.

Stereochemistry:

Both isomers are optically active. Therefore, a total of 4 isomers exist.

Magnetic moment, $\mu=\sqrt{n(n+2)}$

$=\sqrt{3(3+2)}$

$=\sqrt{15}$

∼ 4BM

(iv) Cs[FeCl4]

IUPAC name: Caesium tetrachloroferrate (III)

Oxidation state of Fe = +3

Electronic configuration of d6 = eg2t2g3

Coordination number = 4

Shape: tetrahedral

Stereochemistry: optically inactive

Magnetic moment:

$\mu=\sqrt{n(n+2)}$

$=\sqrt{5(5+2)}$

$=\sqrt{35} \sim 6 \mathrm{BM}$

(v) K4[Mn(CN)6]

Potassium hexacyanomanganate(II)

Oxidation state of manganese = +2

Electronic configuration: d5+: t2g5

Coordination number = 6

Shape: octahedral.

Streochemistry: optically inactive

Magnetic moment, $\mu=\sqrt{n(n+2)}$

$=\sqrt{1(1+2)}$

$=\sqrt{3}$

$=1.732 \mathrm{BM}$