Q7(c)(ii). Structures and magnetic behaviour of Co₂(CO)₈
Elucidate the structure(s) of Co₂(CO)₈. Comment on its magnetic behaviour.
Answer in brief
In the solid Co₂(CO)₈ has a bridged structure, (OC)₃Co(μ-CO)₂Co(CO)₃, with a Co–Co bond, in equilibrium in solution with unbridged (OC)₄Co–Co(CO)₄; every form obeys the 18-electron rule and is diamagnetic.
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Coversdicobalt octacarbonyl18-electron rulebridging carbonylmetal–metal bondfluxional carbonylshydroformylation
All parts of Question 7
- 7(a) Splitting of d orbitals in a square-planar field10 marks
- 7(b)(i) M–C and C–O bond orders in Ni(CO)₄, [Co(CO)₄]⁻ and [Fe(CO)₄]²⁻10 marks
- 7(b)(ii) Identify A, B and C5 marks
- 7(c)(i) [CoF₆]³⁻ paramagnetic, [Co(CN)₆]³⁻ diamagnetic10 marks
- 7(c)(ii) Structures and magnetic behaviour of Co₂(CO)₈15 marks