(a) Fluoride is smaller than chloride (so it should form stronger ionic bonds with metal centers), but fluoride is below chloride in the spectrochemical series. Explain this contradiction.
(b) Ligands with T-acceptor properties (such as carbonyl) have large values of Δ, but ligands with T-donor properties (such as oxide) have small values of Δ. Explain this observation in light of the octahedral MO scheme for transition metal complexes, sketching the orbitals involved in (M-L)σ-bonding.