[单选题]
The complex ion $[Cu(NH_3)_4]^{2+}$ appears a deep blue color in aqueous solution, whereas $[CuCl_4]^{2−}$ appears a green color in aqueous solution. Which of the following statements are correct regarding the two complexes?
I. $[CuCl_4]^{2−}$ appears a green color as a result of the red light being absorbed because $Cl^−$ is a weaker field ligand than $NH_3$
II. $[Cu(NH_3)4]^{2+}$ appears a deep blue color as a result of the blue light being absorbed because $NH_3$ is a stronger field ligand than $Cl^−$
III. $[Cu(NH_3)_4]^{2+}$ appears a deep blue color as a result of the orange light being absorbed because $NH_3$ is a stronger field ligand than $Cl^−$
A. $I$, $II$, and $III$
B. $I$ and $II$ only
C. $II$ and $III$ only
D. $I$ and $III$ only
参考答案:
D
本题详细解析:
Explanation:
The splitting of the d-orbitals in the $[Cu(NH_3)_4]^{2+}$ ion creates an energy difference that corresponds to the absorption of light in the orange part of the visible spectrum.
The complex appears blue because the complementary color of orange is blue. In the case of $[CuCl_4]^{2−}$, the chloride ligand has a lower electron density than ammonia.
The splitting of the d-orbitals creates an energy difference that is less in chloride than ammonia and corresponds to the absorption of light in the red part of the visible spectrum. The complex appears green because the complementary color of green is red.
