Name: Coordination Compounds and Double Salts
Uploaded: 2019-07-19
Duration: 9 min 25 s
Description: Double salts and coordination compounds are complex compounds, and these complexes are of immense importance in various fields. Watch this video and learn th...

Question

Distinguish between inner and outer orbital complex with suitable examples.

Accepted Answer

When the complex formed involves the use of outer $n$ $d -$ orbitals for hybridization $({sp}^{3} d^{2})$ , the complex is called the outer orbital complex. When the complex formed involves the inner $(n - 1) d -$ orbitals for hybridization $(d^{2} {sp}^{3})$ , the complex is called the inner orbital complex. For example, complex ${[Co {({NH}_{3})}_{6}]}^{3 +}$ involves inner $(n - 1)$ $d -$ orbitals. Therefore, it is called the inner orbital complex. Whereas, ${[Ni {({NH}_{3})}_{6}]}^{2 +}$ involves $n d -$ orbitals. Therefore, it is an outer orbital complex.
In ${[Co {({NH}_{3})}_{6}]}^{3 +}$ complex, the oxidation number of $Co = + 3$ . According to Hund's rule, the number of unpaired electrons in 3d-subshell of ${}_{27}{Co} [({}_{18}{Ar}) 3 d^{7} 4 s^{2}]$ is three while in ${Co}^{3 +}$ ion $[({}_{18}{Ar}) 3 d^{6}]$ there are four unpaired electrons.

Whereas, in the case of ${[Ni {({NH}_{3})}_{6}]}^{2 +}$ , the electronic configuration of ${}_{28}{Ni} [(Ar) 3 d^{8} 4 s^{2}]$ and that of ${Ni}^{2 +}$ is $[(Ar) 3 d^{8} 4 s^{0}]$ . In the complex $({NH}_{3})$ is a strong field ligand but if pairing occurs only one $d -$ orbital will be available so it cannot undergo $d^{2} {sp}^{3}$ hybridization.

$3 d 4 s 4 p 4 d Ni - atom ⥮ ⥮ ⥮ ↑ ↑ ⥮ {Ni}^{+ 2} (II) ⥮ ⥮ ⥮ ↑ ↑ {[Ni {({NH}_{3})}_{6}]}^{2 +} ⥮ ⥮ ⥮ ↑ ↑ \underset{{NH}_{3}}{* *} \underset{{NH}_{3}}{* *} \underset{{NH}_{3}}{* *} \underset{{NH}_{3}}{* *} \underset{{NH}_{3}}{* *} \underset{{NH}_{3}}{* *}$

Distinguish between inner and outer orbital complex with suitable examples.

Important Questions on Co-ordination Compounds

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