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GATE 2023 CY – Question 53

Inorganic Chemistry · Organometallics: 18-Electron rule; metal-alkyl, metal-carbonyl, metal-olefin and metal-carbene complexes and metallocenes. Fluxionality in organometallic complexes. Types of organometallic reactions. Homogeneous catalysis – Hydrogenation, hydroformylation, methanol to acetic acid process, olefin metathesis and Wacker oxidation. Heterogeneous catalysis – Fischer-Tropsch reaction, Ziegler-Natta polymerization. · 2 marks · Multiple select

Which statements about $Co_2(CO)_8$ are correct?

  1. It reacts with Na to give $Na[Co(CO)_4]$
  2. It contains three bridging carbonyls
  3. It can be prepared by reductive carbonylation of $Co(OAc)_2\cdot4H_2O$
  4. Two isomers exist in hexane solution

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Correct answer: (A) It reacts with Na to give $Na[Co(CO)_4]$; (C) It can be prepared by reductive carbonylation of $Co(OAc)_2\cdot4H_2O$; (D) Two isomers exist in hexane solution

Explanation

Sodium reductively cleaves the Co–Co bond to form Na[Co(CO)4], A true. Dicobalt octacarbonyl can be made by reductive carbonylation of cobalt acetate, C true. Bridged and unbridged isomers coexist in solution, D true. The bridged isomer has two, not three, bridging CO ligands, so B false. **Select A, C, D**.