Optical isomerism is common in octahedral complexes of the formula $$\left[ {M{a_2}{b_2}{c_2}} \right],\left[ {M{{\left( {AA} \right)}_3}} \right],$$ etc. $${\left[ {Cr{{\left( {en} \right)}_3}} \right]^{3 + }}$$ shows optical isomerism and exists as a pair of enantiomers.
32.
Match the complex ions given in column I with their colour given in column II and mark the appropriate choice.
No explanation is given for this question. Let's discuss the answer together.
33.
Two isomers of a compound $$Co{\left( {N{H_3}} \right)_3}C{l_3}\left( {M{A_3}{B_3}\,{\text{type}}} \right)$$ are shown in the figures.
The isomers can be classified as
A
(i) $$fac$$ - isomer (ii) $$mer$$ - isomer
B
(i) optical-isomer (ii) $$trans$$ - isomer
C
(i) $$mer$$ - isomer (ii) $$fac$$ - isomer
D
(i) $$trans$$ -isomer (ii) $$cis$$ -isomer
Answer :
(i) $$fac$$ - isomer (ii) $$mer$$ - isomer
Chromium in $$Cr{\left( {CO} \right)_6}$$ is in zero oxidation state and has $${\left[ {Ar} \right]^{18}}3{d^5}4{s^1}$$ as the electronic configuration. However, $$CO$$ is a strong ligand, hence pairing up of electrons takes place leading to following configuration in $$Cr{\left( {CO} \right)_6}.$$
Since the complex has no unpaired electron, its magnetic moment is zero.
37.
Which of the following is not a neutral ligand ?
In metal carbonyl $$M\left( {C{O_4}} \right),$$ metal is bonded to the ligand $$CO$$ through carbon atoms. These compounds contain both $$\sigma $$ and $$\pi $$ - bonded complexes.
$$\sigma $$ - bond between metal and carbon atom is formed when a vacant hybrid orbital of the metal atom overlaps with an orbital on $$C$$ - atom of carbon monooxide containing a low pair of electron. Formation of $$\pi $$ - bond is occurs when a filled orbital of the metal atom overlaps with a vacant antibonding $$\pi $$ - orbital of $$C$$ - atom of $$Co.$$
39.
The charges $$x$$ and $$y$$ on the following ions are
$$\eqalign{
& \left( {\text{i}} \right){\left[ {Co{{\left( {N{H_3}} \right)}_2}C{l_4}} \right]^x} \cr
& \left( {{\text{ii}}} \right){\left[ {Fe{{\left( {CN} \right)}_6}} \right]^y} \cr} $$
( Oxidation state of $$Co$$ is +3 and $$Fe$$ is +2 in their respective complexes. )
In $${\left[ {Co{{\left( {N{H_3}} \right)}_2}C{l_4}} \right]^x},$$
oxidation state of $$Co = +3$$
Hence, $$x = + 3 + 2 \times 0 + 4 \times ( - 1){\text{ }} = - 1$$
In $${\left[ {Fe{{\left( {CN} \right)}_6}} \right]^y},$$ oxidation state of $$Fe = +2$$
Hence, $$y = + 2 + 6 \times \left( { - 1} \right) = - 4$$
40.
Red precipitate is obtained when ethanol solution of dimethylglyoxime is added to ammoniacal $$Ni\left( {{\text{II}}} \right){\text{.}}$$ Which of the following statements is not true ?