Question
Download Solution PDFThe 2Eg → 2A2g transition in the electronic spectrum of [Cr(NH3)6]3+ occurs nearly at -
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
The electronic transition in coordination chemistry involves the movement of an electron from one d-orbital to another, leading to absorption of light at specific wavelengths.
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The [Cr(NH3)6]3+ complex is an octahedral complex with chromium in the +3 oxidation state.
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2Eg and 2A2g refer to specific electronic states derived from the d-orbital splitting in an octahedral field.
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Transition metal complexes often show electronic absorption bands in the visible to ultraviolet region.
Explanation:
Orgel diagrams are used to understand the electronic transitions in transition metal complexes, especially d-d transitions. In an octahedral field, the d-orbitals split into two sets: t2g (lower energy) and eg (higher energy).
For a d3 configuration like Cr3+ in [Cr(NH3)6]3+, the possible electronic states are derived from the combination of three d-electrons occupying the split d-orbitals.
The ground state term is 4A2g, and the excited states involve transitions between the split orbitals, resulting in specific bands in the electronic spectrum. According to Orgel theory:
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The 2Eg state corresponds to the first excited state of the electron configuration.
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The 2A2g state corresponds to another excited state at a higher energy level.
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The transition from 2Eg to 2A2g involves the promotion of an electron within the split d-orbitals.
The energy difference between these states, and hence the specific wavelength of light absorbed, can be estimated using an Orgel diagram for the d3 configuration. For [Cr(NH3)6]3+, this transition commonly occurs around 450 nm.
Conclusion:
Based on Orgel theory, the 2Eg → 2A2g transition in the electronic spectrum of [Cr(NH3)6]3+ occurs nearly at 450 nm, corresponding to the visible region of light.
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