Coordination Compounds

Chemistry

NCERT

1   Write the formulas for the following coordination compounds:$\\$ (i) Tetraamminediaquacobalt (III) chloride$\\$ (ii) Potassium tetracyanonickelate(II)$\\$ (iii) Tris(ethane-1,2-diamine) chromium(III) chloride$\\$ (iv) Amminebromidochloridonitrito-N-platinate(II)$\\$ (v) Dichloridobis(ethane-1,2-diamine)platinum(IV) nitrate$\\$ (vi) Iron(III) hexacyanoferrate(II)

Solution :

(i)$[CO(H_2O)(NH_3)_4]Cl_3$$\\$ (ii)$K_2[Ni(CN)_4]$$\\$ (iii)$[Cr(en)_3]Cl_3$$\\$ (iv)$[Pt(NH)_3 BrCl(NO_2)]$$\\$ (v)$[PtCl_2(en)_2(NO_3)_2]$$\\$ (vi)$Fe_4[Fe(CN)_6]_3$

2   Write the $IUPAC$ names of the following coordination compounds:$\\$ (i) $[CO ( NH_3 )_8 ] Cl_3$$\\$ (ii) $[CO ( NH_3 )_6 Cl ] Cl_3$$\\$ (iii) $K_3 [ Fe ( CN )_8 ]$$\\$ (iv) $K_3 [ Fe ( C_2 N_4 )_3 $$\\$ (v) $K_2 [ PdCl_4 ]$$\\$ (vi) $[Pt ( NH_3 )_2 Cl ( NH_2 CH_3 ) ] Cl$

Solution :

(i) Hexaamminecobalt(III) chloride$\\$ (ii) Pentaamminechloridocobalt (III) chloride$\\$ (iii) Potassium hexacyanoferrate(III)$\\$ (iv) Potassium trioxalatoferrate(III)$\\$ (v) Potassium tetrachloridopalladate(II)$\\$ (vi) Diamminechlorido(methylamine)platinum(II) chloride

3   Indicate the types of isomerism exhibited by the following complexes and draw the structures for these isomers:$\\$ (i)$K[Cr(H_2O)_2(C_2O_4)_2]$$\\$ (ii)$[CO(en)_2]Cl_2$$\\$ (iii)$[Co(NH_3)_6(NO_2)](NO_3)_2$$\\$ (iv)$[Pt(NH_2)(H_2O)Cl_2]$

Solution :

(i) Both geometrical (cis-, trans-) isomers for $K [Cr ( H_2 O )_2 ( C_2 O_4 )_2 ]$ can exist. Also, optical isomers for cis-isomer exist.$\\$ Trans-isomer is optically inactive. On the other hand, cis-isomer is optically active.$\\$ (ii) Two optical isomers for $[ CO ( en )_2 ] Cl_2$ exist.$\\$ Two optical isomers are possible for this structure.$\\$ (iii)$[CO(NH_3)(NO_2)](NO_3)_2$$\\$ A pair of optical isomers:$\\$ It can also show linkage isomerism.$9741621450$$\\$ $[CO ( NH_3 )_5 ( NO_2 ) ] ( NO_3 )_2$ and $[ CO ( NH_3 )_5 ( ONO ) ] ( NO _3 )_ 2$$\\$ It can also show ionization isomerism.$\\$ $[CO ( NH_3 ) _5 ( NO _2 ) ] ( NO _3 ) _2$ and $ [CO ( NH_3 )_ 5 ( NO_3 ) ] ( NO _3 )( NO _2 )$$\\$ (iv) Geometrical (cis-, trans-) isomers of $[ Pt ( NH _3 )( H _2 O ) Cl _2 ]$ can exist.

4   Give evidence that $[Co(NH_3 )_5 Cl]SO _4$ and $[Co(NH_3 )_5 SO_4 ]Cl$ are ionization isomers.

Solution :

When ionization isomers are dissolved in water, they ionize to give different ions. These ions then react differently with different reagents to give different products.

5   Explain on the basis of valence bond theory that $Ni ( CN )_4 $ ion with square planer structure is diamagnetic and the $Ni ( Cl )_4$ ion with tetrahedral geometry is paramagnetic.

Solution :

Ni is in the $+2$ oxidation state i.e., in $d^ 8$ configuration.$\\$ There are $4 CN ^-$ ions. Thus, it can either have a tetrahedral geometry or square planar geometry. Since $CN ^- $ ion is a strong field ligand, it causes the pairing of unpaired $3d$ electrons. $\\$ It now undergoes $\text{dsp }^2$ hybridization. Since all electrons are paired, it is diamagnetic. In case of $[NiCl_4] ^{2-}, Cl ^-$ ion is a weak field ligand. Therefore, it does not lead to the pairing of unpaired $3d$ electrons.