Chemistry · IUPAC nomenclature of mononuclear co-ordination compounds, isomerism

Select the correct I.U.P.A.C name for _{4}\right] \)

Select the correct I.U.P.A.C name for \( \boldsymbol{N} \boldsymbol{a}\left[\boldsymbol{C o}(\boldsymbol{C O})_{4}\right] \)

  • A. Sodium tetracarbonylcobalt (-I)
  • B. Sodium tetracarbonylcobalt (0)
  • C. Sodium tetracarbonylcobaltate (0)
  • D. sodium tetracarbonylcobaltate (-I)

Step-by-step solution

The compound Na[Co(CO)4] consists of the cation Na+ and the complex anion [Co(CO)4]^-. According to IUPAC rules, anionic complexes use the suffix '-ate' attached to the metal name. Each CO ligand is neutral, so the oxidation state of Co is determined from the overall charge: x + 4(0) = -1 → x = -1. Thus, the correct name is sodium tetracarbonylcobaltate(-I). Options A and B incorrectly omit '-ate', and option C gives an incorrect oxidation state.
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