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GATE 2022 CY – Question 55

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

The compound(s) that satisfies/satisfy the 18-electron rule is(are) (Atomic number of Os = 76, Rh = 45, Mo = 42, and Fe = 26)

Diagram for GATE 2022 CY question 55
  1. Diagram A
  2. Diagram B
  3. Diagram C
  4. Diagram D

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Show answer and explanation

Correct answer: (A) Diagram A; (D) Diagram D

Explanation

In A, each Rh(I)d8 receives 6e from Cp,2e from two bridging CO contributions and 2e from two Rh–Rh bonds, total 18. In D, Os(II)d6+η6-arene6e+diimine4e+chloride2e=18. B and C are electron-deficient under the depicted metal–metal bonding: the Mo centres have 16e and the Fe centres 17e. **Select A, D**.