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Of the complexes, [crcl6]3-, [cr(h2o)6]3+, [cr(en)3]3+, [cr(ox)3]3-, which would present a peak with the shortest wavelength
Accepted Answer
The complex [CrCl6]3- would present a peak with the shortest wavelength. Here's why:
Ligand Field Theory: The color of transition metal complexes arises from the absorption of light, causing an electron to jump from a lower energy d-orbital to a higher one. This energy difference is influenced by the ligands surrounding the metal ion.
Spectrochemical Series: The spectrochemical series ranks ligands based on their ability to split the d-orbitals. Ligands that cause a larger splitting lead to higher energy differences and thus, shorter wavelength absorption (higher energy light).
In this case: Chloride ions (Cl-) are weak field ligands, leading to a smaller d-orbital splitting. Water (H2O) is a stronger field ligand, and ethylenediamine (en) and oxalate (ox) are even stronger. The stronger the ligand field, the larger the splitting, and the longer the wavelength of the absorbed light.
Therefore, [CrCl6]3- with the weakest field ligands, will absorb the highest energy light (shortest wavelength).
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