Answer: Hard (sigma-donor) ligands stabilise hard metal centres; soft (pi-acceptor) ligands stabilise soft centres (HSAB principle applied to complexes).
- A Hard (sigma-donor) ligands stabilise hard metal centres; soft (pi-acceptor) ligands stabilise soft centres (HSAB principle applied to complexes)
- B Every ligand type is said to behave in an largely equivalent way regardless of hard or soft donor character according to standard textbooks
- C Mainly strong field ligands such as CN- are said to ever be capable of forming any reasonably stable complex in general practice as frequently described
- D The coordination number on its own is said to be the single factor that largely determines complex stability in most textbook accounts during normal conditions
Correct answer: A. Hard (sigma-donor) ligands stabilise hard metal centres; soft (pi-acceptor) ligands stabilise soft centres (HSAB principle applied to complexes)
Explanation: HSAB principle: hard metal centres (high charge, low polarisability) bind preferentially with hard ligands (F-, OH-, O donors); soft metals (Pt, Pd, Hg) bind soft ligands (I-, S donors, CO, CN-).
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.