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🧪 Chemistry  ·  Coordination Compounds  ·  NEET & JEE

The fluxional behaviour of [Fe(CO)<sub>5</sub>] (trigonal bipyramidal) refers to:

Answer: Rapid exchange of axial and equatorial CO positions at room temperature via Berry pseudorotation.

  • A Rapid exchange of axial and equatorial CO positions at room temperature via Berry pseudorotation
  • B A largely fixed, rigid structure with little exchange between CO positions as generally observed
  • C Permanent loss of one CO ligand followed by its slow recoordination in typical laboratory settings
  • D Spontaneous ring formation among the five coordinated CO ligands under usual circumstances

Correct answer: A. Rapid exchange of axial and equatorial CO positions at room temperature via Berry pseudorotation

Explanation: Berry pseudorotation in Fe(CO)<sub>5</sub>: a concerted movement interconverts axial and equatorial CO positions; 13C NMR shows all 5 CO equivalent even at room temperature.

Octahedralcoordination no. 6e.g. [Co(NH3)6]3+Tetrahedralcoordination no. 4e.g. [Ni(CO)4]Square Planarcoordination no. 4e.g. [Pt(NH3)2Cl2]

The three common coordination geometries: octahedral (6 ligands), tetrahedral (4 ligands), and square planar (4 ligands in one plane).

Concept context

Study of compounds where a central metal atom is bonded to surrounding ligands. Covers nomenclature, types of isomerism, bonding theories (VBT, CFT), and applications in medicine, photography, and industry.

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