Give the oxidation state, d-orbital occupation and coordination number of the central metal ion in the following complexes: (i) \mathrm{K}_{5}\left[\mathrm{Co}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]
Give the oxidation state, d-orbital occupation and coordination number of the central metal ion in the following complexes: (i) \mathrm{K}_{5}\left[\mathrm{Co}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]

Ans: The complex will be \left[\mathrm{Co}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{8}\right]^{3}.
Oxidation state of cobalt will be =x-6=-3
The oxidation state is =+3
Coordination number =6
In +3 oxidation state of Co the configuration is 3 d^{\circ}.
So, the configuration will be \mathrm{t}_{\mathrm{sp}}^{6} \mathrm{e}_{0}^{0}
(ii) \left(\mathrm{NH}_{2}\right)_{2}\left[\mathrm{CoF}_{4}\right]
Ans: The complex will be \left[\mathrm{CoF}_{4}\right]^{2}.
Oxidation state of cobalt will be =x-4=-2
The oxidation state is =+2
Coordination number =4
In +2 oxidation state of Co the configuration is 3 \mathrm{~d}^{2}.
So, the configuration will be
(iii) cis-[Cr(en) \left.\mathrm{Cl}_{2}\right] \mathrm{Cl}
Ans: The complex will be \left[\mathrm{Cr}(\mathrm{en})_{2} \mathrm{Cl}_{2}\right]^{+}.
Oxidation state of chromium will be =x+0-2=+1
The oxidation state is =+3
Coordination number =6
In +3 oxidation state of \mathrm{Cr} the configuration is 3 \mathrm{~d}^{3}.
So, the configuration will be \mathrm{t}_{\mathrm{ij}}^{\mathrm{2}}
(iv) \left[\mathrm{Mn}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right] \mathrm{SO}_{4}
Ans: The complex will be \left[\mathrm{Mn}\left(\mathrm{H}_{2} \mathrm{O}\right)_{8}\right]^{2+}.
Oxidation state of manganese will be =x+0=+2
The oxidation state is =+2