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Coordination Compounds
Question
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(a) Write the hybridization and shape of the following complexes:

(i) [CoF6]3–

(ii) [Ni (CN)4]2–

(Atomic number: Co = 27, Ni = 28)


(b) Out of NH3 and CO, which ligand forms a more stable complex with a transition metal and why?

Answer

(a)
(i) The atomic number of Co is 27 and its valence shell electronic configuration is 3d74s2.

Co is in +3 oxidation state in the complex [CoF6]3-.

 

Hence, [CoF6]3- is sp3d2 hybridized and it is octahedral in shape.

 

(ii) The atomic number of Ni is 28 and its valence shell electronic configuration is 3d84s2.

Ni is in +2 oxidation state in the complex [Ni(CN)4]2–.

Hence, [Ni(CN)4]2– is dsp2 hybridized and it is square planar in shape.

 

(b) Out of NH3 and CO, CO ligand forms a more stable complex with transition metal because the metal- carbon bonds in metal carbonyls have both  and  characters .A  bond is formed when carbonyl carbon donates a lone pair of electrons to the vacant orbital of the metal. A  bond formed by the donation pair of electrons from filled metal d orbital into the vacant anti- bonding orbital ( also known as back bonding  of the carbonyl group). And sigma bond strengthen the pi bond vice-versa. Thus, a synergic effect s created due to this metal- ligand bonding. These synergic effects strengthen the bond between CO and the metal.

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Some More Questions From Coordination Compounds Chapter

Write the formula for the following coordination compound:
Potassium tetracyanidonickelate(II)

Write the formula for the following coordination compound:
Tris(ethane -1, 2-diamine) chromium(III) chloride

Write the formula for the following coordination compound:
Amminebromidochloridonitrito-N-platinate (II)

Write the formula for the following coordination compound:
Dichloridobis(ethane-1, 2-diamine)platinum(lV) nitrate.

Write the formula for the following coordination compound:
Iron(III) hexacyanidoferrate(II)

Write the IUPAC names of the following coordination compounds:
(i) [Co(NH3)6]Cl3
(ii) [Co(NH3)5Cl]Cl2
(iii) K3[Fe(CN)6]
(iv) K3[Fe(C2O4)3]
(v) K2[PdCl4]
(vi) [Pt(NH3)2Cl(NH2CH3)]Cl.

Indicate the type of isomerism exhibited by the following complexes and draw structures for these isomers:
(i)    K[Cr(H2O)2(C2O4)2],                      (ii) [Co(en)3Cl3,
(iii) [Co(NH3)5(NO2)]|NO3]2,                 (iv) [Pt(NH3)(H2O)Cl2]

Explain on the basis of valence bond theory that [Ni(CN)4]2–  ion with square planar is diamagnetic and the [NiCl4]2– ion with tetrahedral geometry is paramagnetic.