181. What is crystal field splitting energy? How does the magnitude of Δ₀ decide the actual configuration of d orbitals in a coordination entity?

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182. [Cr(NH₃)₆)³⁺ is paramagnetic while [Ni(CN)₄]^{2 –} is diamagnetic. Explain why?

[Cr(NH₃)₆]³⁺: Outer electronic configuration of chromium (Z = 24) in ground state is 3d⁵4s¹ and in this complex it is in the +3 oxidation state. Chromium achieves the +3 oxidation state by the loss of one 4s electron and two 3d-electrons. The resulting Cr³⁺ ion has outer electronic configuration of 3d³. The two vacant 3d-orbitals, one 4s-orbital and three 4p-orbitals hybridise to give six equivalent d²sp³ hybrid orbitals. Six pairs of electrons, one from each NH₃ molecule occupy the six vacant hybrid orbitals so produced. The resulting complex ion has one octahedral geometry. Since the complex contains three unpaired electrons, it is paramagnetic.

[Ni(CN)₄]^2– : Outer electronic configuration of nickel (Z = 28) in ground state is 3d ⁸4s². Nickel in this complex is in the +2 oxidation states. It achieves +2 oxidation state by the loss of the two 4s- electrons. The resulting of Ni²⁺ ion has outer electronic configuration of 3d⁸. The two unpaired 3d- electrons are forced to pair up.

The resulting vacant 3d-orbital along with the 4s-orbital and two 4p-orbitals hybridised to give four equivalent dsp² hybridised orbitals. Four pairs of electrons, one from each cyanide ion occupy the four vacant hybrid orbitals so produced. Therefore, it is diamagnetic because there is no unpaired electrons.

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183.

Discuss the nature of bonding in metal carbonyls.

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184.

Give the oxidation state, d-orbital occuptaion and coordination number of the central metal ion in the following complexes:
K₃[Co(C₂O₄)₃]

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185.

Give the oxidation state, d-orbital occuptaion and coordination number of the central metal ion in the following complexes:
cis-[Cr(en) ₂Cl₂]Cl

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186.

Give the oxidation state, d-orbital occuptaion and coordination number of the central metal ion in the following complexes:
(NH₄)₂[CoF₄]

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187.

Give the oxidation state, d-orbital occuptaion and coordination number of the central metal ion in the following complexes:
[Mn(H₂O)₆SO₄

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188.

Write down the IUPAC name for each of the following complexes and indicate the oxidation state, electronic configuration & coordination number, Also give stereochemistry and magnetic moment of the complex:
K[Cr(H₂O)₂(C₂O₄)₂]. 3H₂O

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189.

Write down the IUPAC name for each of the following complexes and indicate the oxidation state, electronic configuration & coordination number, Also give stereochemistry and magnetic moment of the complex:
CrCl₃(py)₃

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190.

Write down the IUPAC name for each of the following complexes and indicate the oxidation state, electronic configuration & coordination number, Also give stereochemistry and magnetic moment of the complex:
Cs[FeCl₄].

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