Inorganic Chemistry

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inner and outer orbital complexes
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inner and outer orbital complexes



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3 Jan 2011 14:59:50 IST
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9 Jan 2011 18:30:50 IST
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complexes showing d2sp3 hybridization are called inner orbital octahedral complexes because they use inner 3d orbitals in hybridization,whereas those showing sp3d2 are called outer orbital complexes as they use outer 4d orbitals(in case of first transition metals)......

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12 Jan 2011 17:46:34 IST
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Introduction to inner and outer orbital complexes

Definition of complexes: Complexes are the compounds where the ligands from one or more coordinate bond with metal atoms/ions.

If (n-1)d orbital’s are used for hybridization, then complexes are called inner orbital complexes and these complexes involves d2sp32O)6]3+, [Co(NH3)6]3+ hybridization, and are either diamagnetic or have lesser number of unpaired electrons. Example: [V(H

If (n)d orbital’s are used for hybridization, such complexes are called outer orbital complexes.These complexes involves sp3dhybridization and posses more number of electrons.

Inner and Outer Orbital Complexes

Formation of [Cr (NH3)6]3+ ion is inner orbital complexes. Chromium is in +3 oxidation state. The electronic configuration of chromium (atomic number24) and Cr+3 ions.

Electronic configuration of Cr = [Ar] 3d5 4s1

Electronic configuration of Cr3+ = [Ar] 3d3

Now since 3p orbitals are completely filled they do not take part in chemical bonding and hence called non bonding electrons. These are generally omitted in picturising the structure of the complete ion where only orbitals involved in bond formation are drawn, thus in this case3d, 4s and 4p orbitals.

Now since two 3d, one 4s and 4p orbital (all of nearly same energy) are to be used for metal –ligand bonding, i.e, for accommodating six ligand molecules, they must hybridise to give six d2sp3 hybrid orbitals of equal energy so that they give same properties and equal energy to all the metallagand bonds.

The resulting six d2sp3 hybrid orbitals are occupied by the electron pairs donated by six ligand molecule, each donating one lone pair. As we know the d2sphybridisation leads to octahedral geometry. The complex [Cr (NH3)6]3+ will be octahedral in shape.

Formation of [Ni (CN4)] 2-  is outer orbital complexes:

Since the coordination number of Ni in the complex is 4, the configuration of Ni+2 , at first sight, shows that the complex is formed by sp 3 hybridization  and it is paramagnetic and it has two unpaired electrons. However, experiments show that the complex is diamagnetic, i.e. it do not have unpaired electrons, this is possible when 3d electrons rearrange against the hund’s rule as shown in the below configuration. This is also in accordance with the fact that the ligand involved here is a strong i.e. CN- ion.

 Hence now dsp2 hybridization, involving one 3d, one 4s and two 4p orbitals, takes place leading to four dsp2 hybrid orbitals, each of which accepts four electron pairs from CN ion forming [Ni (CN4)] 2 ion. Thus the resulting complex is square planar and is diamagnetic as it has no unpaired electrons.

Electronic Configuration of Inner and Outer Orbital Complex:

The electronic configuration of inner orbital complex chromium atom and Cr3+ ion may be shown as below.

The electronic configuration of the nickel atom and Ni+2 ion are depicted below.




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19 Jun 2012 13:18:26 IST
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and what about higer and less electromagnetic orbitals



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