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Indian Forest Service (Mains)

Chemistry optional

  • 2 papers
  • 200 marks each
  • 3 h per paper

Paper I covers physical and inorganic chemistry.

Indian Forest Service (Mains), Chemistry optional · 2025 · Paper I

Q5(d). Dicobalt octacarbonyl

Question

Describe the structure of Co₂(CO)₈ and distinguish terminal and bridging carbonyl groups using IR spectroscopy.

Answer in brief

The familiar bridged structure contains a Co–Co bond, six terminal carbonyls and two bridging carbonyls; bridging CO absorbs at lower wavenumber.

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Topic notes: metal carbonyls, nitrosyls, the 18-electron and EAN rules, metal–metal bonds and clusters, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversdicobalt octacarbonyl Co₂(CO)₈bridging carbonylterminal carbonylIR stretching frequency of COback-bonding

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