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UPSC Civil Services (Mains)

Chemistry optional

  • 2 papers
  • 250 marks each
  • 3 h per paper
  • 5 of 8 questions, Q1 and Q5 compulsory

Paper I covers physical and inorganic chemistry.

UPSC Civil Services (Mains), Chemistry optional · 2022 · Paper I

Q8(a). The more stable linkage isomer of a cyanide-bridged complex

Question

Which one is more stable between the two isomers? Explain. [(H₃N)₅Cr–CN–Cr(CN)₅] and [(H₃N)₅Cr–NC–Cr(CN)₅]

Answer in brief

The second, [(H₃N)₅Cr–NC–Cr(CN)₅]: its bridging cyanide is bonded through carbon to the chromium carrying five cyanides and through nitrogen to the chromium carrying five ammonias.

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Coverslinkage isomerismambidentate ligandcyanide bridgeHSAB symbiosishard and soft acids and bases

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