Answer: H 2 O is a pi-donor (lone pairs on O donate into empty metal d orbitals), decreasing effective Delta; NH 3 has no pi-donor capacity.
- A H<sub>2</sub>O is a pi-donor (lone pairs on O donate into empty metal d orbitals), decreasing effective Delta; NH<sub>3</sub> has no pi-donor capacity
- B Water is actually claimed to be a far stronger sigma donor than ammonia toward the metal centre under usual circumstances according to most researchers
- C Ammonia is instead claimed to accept pi electron density back from the filled metal d orbitals in the majority of cases studied
- D Water's oxygen donor atom is generally claimed to be much larger than ammonia's nitrogen donor atom as widely reported in standard practice
Correct answer: A. H<sub>2</sub>O is a pi-donor (lone pairs on O donate into empty metal d orbitals), decreasing effective Delta; NH<sub>3</sub> has no pi-donor capacity
Explanation: H<sub>2</sub>O donates both sigma (into metal's empty orbital) and pi (from O lone pair back into metal d), partially cancelling sigma donor effect. NH<sub>3</sub> is a pure sigma donor giving higher net Delta.
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.