Answer: [Co(NH 3 ) 6 ]Cl3 and its series of Co-NH 3 -Cl complexes.
- A [Co(NH<sub>3</sub>)<sub>6</sub>]Cl3 and its series of Co-NH<sub>3</sub>-Cl complexes
- B NaCl, a simple ionic salt with no coordinate covalent bonding
- C [Pt(CN)4]2-, a square planar complex unrelated to Werner's original series
- D K<sub>4</sub>[Fe(CN)<sub>6</sub>], the separate potassium ferrocyanide salt
Correct answer: A. [Co(NH<sub>3</sub>)<sub>6</sub>]Cl3 and its series of Co-NH<sub>3</sub>-Cl complexes
Explanation: Werner's studies on cobalt-ammonia complexes (e.g., [Co(NH<sub>3</sub>)<sub>6</sub>]Cl3, [Co(NH<sub>3</sub>)5Cl]Cl<sub>2</sub>, etc.) established the concept of primary and secondary valence.
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.