Which coordination polyhedron does [Ni(CO)₄] adopt?

1. Your syllabus explicitly gives [Ni(CO)₄] as an example of a tetrahedral complex. 2. Ni(0) with 4 CO ligands has d¹⁰ configuration. 3. CO is a strong-field ligand, but Ni(0) in [Ni(CO)₄] is tetrahedral in geometry. 4. [PtCl₄]²⁻ (d⁸) is square planar; [Co(NH₃)₆]³⁺ (d⁶) is octahedral. _Source: syllabus Chemistry, Unit 5 "Coordination Compounds", §5.2(f)_