Answer: It is a good sigma and pi acceptor (back-bonding with metal d orbitals causes large Delta).
- A It is a good sigma and pi acceptor (back-bonding with metal d orbitals causes large Delta)
- B It generally carries a negative charge like many weak field ligands also do as frequently observed in practice
- C It has an unusually small ionic size compared to other ligands in many documented cases
- D It happens to contain a nitrogen atom in its structure according to conventional understanding
Correct answer: A. It is a good sigma and pi acceptor (back-bonding with metal d orbitals causes large Delta)
Explanation: CN- is a strong pi-acceptor; it accepts electron density from filled metal d orbitals into its pi* orbital (back-bonding), causing large crystal field splitting.
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.