Table 2. Values of Second Order Crystal Field Terms for Eu(III) Complexesa.
| complex | B02, cm–1 | B22, cm–1 |
|---|---|---|
| [EuLla] | <−200d | 0 |
| [EuL2a] | <+200d | 0 |
| [EuL3]3+ | +230d | 0 |
| [EuL4(H2O)]3+ | –470b | 0 |
| [EuL5a]− | –700 | 0 |
| [EuL5b]− | –650 | 0 |
| [EuL6] | –550 | –145 |
| [EuL7] | –455 | –120 |
| [EuL8a] | –660 | –122 |
| [EuL8b] | –650 | –80 |
| [EuL9]+ | +735c | –220c |
a
From emission spectra at 295 K in H2O. Ligand field parameter values quoted in the spherical tensor formalism.
b
With different axial donors, values changed dramatically, for example, MeCN (−630), DMF (−340), DMSO (−150), and HMPA (−85), and with fluoride replacing the coordinated water molecule, B02 has a positive sign.
c
In methanol, values were +920 and −153 cm–1.
d
Data recorded in methanol, not water, where values are smaller; the value for [EuL2a] represents an upper limit, owing to the lack of spectral resolution.