Q2(b)(i). Regular and flattened tetrahedra
Discuss the following observation: (i) The [CoCl₄]²⁻ ion is a regular tetrahedron but [CuCl₄]²⁻ has a flattened tetrahedral structure.
Answer in brief
Tetrahedral Co²⁺ (d⁷) has an orbital-singlet ground state; Cu²⁺ (d⁹) has an orbitally degenerate ground state that is stabilised by flattening.
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CoversJahn-Teller distortion[CuCl4]2-[CoCl4]2-tetrahedral complexesflattened tetrahedron
All parts of Question 2
- 2(a)(i) Fluorite and antifluorite5 marks
- 2(a)(ii) Schottky and Frenkel defects5 marks
- 2(a)(iii) Normal and inverse spinels5 marks
- 2(b)(i) Regular and flattened tetrahedra5 marks
- 2(b)(ii) Two bands in high-spin [CoF₆]³⁻5 marks
- 2(c) Polymorphism in crystals5 marks