Q7(a)(ii). Structure of Fe₂(CO)₉ and the 18-electron rule
Write the structure of Fe₂(CO)₉. Show that each iron atom in the structure conforms to the 18e rule.
Answer in brief
Two Fe(CO)₃ units linked by three bridging CO ligands and an Fe–Fe bond (D₃ₕ). Each Fe: 8 (Fe) + 6 (three terminal CO) + 3 (three μ₂-CO, one electron to each Fe) + 1 (Fe–Fe bond) = 18 electrons.
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All parts of Question 7
- 7(a)(i) Metal carbonyls; how they are formed; tetrahedral Ni(CO)₄10 marks
- 7(a)(ii) Structure of Fe₂(CO)₉ and the 18-electron rule10 marks
- 7(b) Ferredoxin: structure and role in photosynthesis10 marks
- 7(c) Isomers of [CoCl₂(en)₂]⁺; is there a meso form?10 marks