Question

Write down the IUPAC name for each of the following complexes and indicate the oxidation state, electronic configuration and coordination number. Also give stereochemistry and magnetic moment of the complex:
$(i) K[Cr(H_2O)_2(C_2O_4)_2].3H_2O$
$(ii)[Co(NH_3)_5Cl]Cl_2$
$(iii) CrCl_3(py)_3$
$(iv) Cs[FeCl_4]$
$(v)K_4[Mn(CN)_6]$

Answer 1

(i) Potassium diaquadioxalatochromate (III) trihydrate.
Oxidation state of chromium=3
Electronic configuration: $3d ^{3} : t_{2g}^ 3$
Coordination number = 6 Shape: octahedral
Stereochemistry:

Magnetic moment, $ÃŽÂ\frac{1}{4}=\sqrt{n(n+2)}$
$=\sqrt{3(3+2)}$
$=\sqrt{15}$
$∼ 4BM$

$(ii) [Co(NH_3)_5Cl]Cl_2$
IUPAC name: Pentaamminechloridocobalt(III) chloride
Oxidation state of $Co=+3$
Coordination number=6 Shape: octahedral.
Electronic configuration: $d ^{6} : t_{2g}^ 6 .$
Stereochemistry:

Magnetic Moment=0

$(iii) CrCl_3(py)_3$
IUPAC name: Trichloridotripyridinechromium (III)
Oxidation state of chromium = +3
Electronic configuration for $d^{ 3} = t_{2g}^ 3$
Coordination number = 6
Shape: octahedral.
Stereochemistry:

Both isomers are optically active.
Therefore, a total of 4 isomers exist.
Magnetic moment$, ÃŽÂ\frac{1}{4}=\sqrt{n(n+2)}$
$=\sqrt{3(3+2)}$
$=\sqrt{15}$
∼ 4BM

$(iv) Cs[FeCl_4]$
IUPAC name: Caesium tetrachloroferrate (III)
Oxidation state of$Fe = +3$
Electronic configuration of $d ^{6} = eg^{ 2} t_{2g}^ 3$
Coordination number = 4 Shape: tetrahedral
Stereochemistry: optically inactive Magnetic moment: $ÃŽÂ\frac{1}{4}=\sqrt{n(n+2)}$
$=\sqrt{5(5+2)}$
$=\sqrt{35}$
~6BM

$(v) K_4[Mn(CN)_6]$ Potassium hexacyanomanganate(II)
Oxidation state of manganese=+2
Electronic configuration: $d ^{5+}: t_{2g}^ 5$
Coordination number = 6 Shape: octahedral.
Streochemistry: optically inactive
Magnetic moment,$ÃŽÂ\frac{1}{4}=\sqrt{n(n+2)}$
$=\sqrt{1(1+2)}$
$=\sqrt{3}$
$=1.732BM$