Why is Fe(bipy)3 low spin, whereas Fe(bipy)2(H2O) high spin?
Common, that's the most basic question, it must be covered in your book. Start with a general question - why are some complexes high spin whereas others are low spin? What does the spin tell about the d orbitals in the complexed metal?
The real question is, "Why does the addition of 2 water ligands change the value of 10Dq so much?"
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