Question

Give the oxidation state, d-orbital occupation and coordination number of the central metal ion in the following complexes:

(i) K₃[Co(C₂O₄)₃]
(ii) cis-[Cr(en)₂Cl_2]Cl
(iii) (NH₄)₂[CoF₄]
(iv) [Mn(H₂O)₆]SO₄

Answer 1

(i) K₃[Co(C₂O₄)₃]
The central metal ion is Co. Its coordination number is 6. The oxidation state can be given as:
x − 6 = −3 x
= + 3
The d orbital occupation for Co³⁺ is t_2g ⁶eg 0.
(ii) cis-[Cr(en)₂Cl₂]Cl
The central metal ion is Cr. 

The coordination number is 6. The
oxidation state can be given as:
x + 2(0) + 2(−1) = +1
x − 2 = +1 x = +3
The d orbital occupation for Cr3+ is t2g 3.

(iii) (NH₄)₂[CoF_4]
The central metal ion is Co.
The coordination number is 4.
The oxidation state can be given as:
x − 4 = −2 x
= + 2
The d orbital occupation for Co²⁺ is eg ⁴ t_2g 3.

(iv) [Mn(H₂O)₆]SO₄
The central metal ion is Mn.
The coordination number is 6. The
oxidation state can be given as: x +
0 = +2 x = +2
The d orbital occupation for Mn is t_2g ³ eg ^2.