Practice question

MCQ

Question

Which complex has a coordination number of 5 and follows the 18-electron rule?

Options

Choose one · Correct answer highlighted

[Co(NH₃)5]3+ [Ni(NH₃)4]2+ [CuCl₄]2− [Fe(CO)5] Correct

Explanation

[Fe(CO)5] (Fe₀, d8) has 5 CO ligands. EAN = 26 + 2 × 5 = 36, but in organometallic context, 8 valence + 10 from ligands = 18 electrons.

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