Final answer:
Hydroxide (OH-) is a weak-field π-donor, ammonia (NH₃) is an intermediate-field σ-donor, and ethylene (CH₂CH₂) is a strong-field π-acceptor, as determined by their positions in the spectrochemical series.
Step-by-step explanation:
The ligands hydroxide (OH-), ammonia (NH₃), and ethylene (CH₂CH₂) can be categorized based on their field strength, which influences their ability to split the d-orbitals in transition metal complexes. The strength of a ligand is related to its ability to act as a π-acceptor, σ-donor, or π-donor:
Hydroxide (OH-) is typically considered a weak-field ligand and a π-donor. This is inferred from its position in the spectrochemical series, which indicates a relatively lower crystal field splitting energy than stronger ligands.
Ammonia (NH₃) is considered an intermediate-field ligand that acts primarily as a σ-donor. It is capable of forming bonds with metal ions through the lone pair of electrons on nitrogen, and it typically causes moderate splitting of d-orbitals.
Ethylene (CH₂CH₂) is generally a strong field ligand and functions as a π-acceptor. It participates in back-bonding with the metal center, which results in greater splitting of the d-orbitals compared to weak and intermediate ligands.
By understanding the placement of these ligands within the spectrochemical series, their relative field strength and bonding characteristics can be deduced.