Table 1. Values for Δ and ligand field stabilization energy for the evaluated metal ion–extractant pairs, as well as the difference in LFSE upon extraction from an aqueous sulfate solution.
| Metal | Extractant | Geometrya | Transition | Value | λ max (nm) | ν max (103 cm−1) | Δ (103 cm−1) | LFSE (103 cm−1) | ΔLFSEwaterb (103 cm−1) |
|---|---|---|---|---|---|---|---|---|---|
| Cu(ii) | LIX 84-I | O h | 2Eg → 2T2g | Δ O | 656 | 15.2 | 15.2 | 9.15 | 1.73 |
| Cu(ii) | Mextral 54-100 | D 4h | dz2 → dx2–y2 | Δ O | 672g | 14.9 | 14.9 | 9.64c | 2.23 |
| Cu(ii) | Versatic acid 10 | O h | 2Eg → 2T2g | Δ O | 677 | 14.5 | 14.5 | 8.72 | 1.30 |
| Cu(ii) | Cyanex 301d | O h | 2Eg → 2T2g | Δ O | 723 | 13.8 | 13.8 | 8.30 | 0.88 |
| Cu(ii) | Water | O h | 2Eg → 2T2g | Δ O | 809 | 12.4 | 12.4 | 7.42 | 0 |
| Cu(ii) | Ionquest 290 | O h | 2Eg → 2T2g | Δ O | 825 | 12.1 | 12.1 | 7.27 | −0.14 |
| Cu(ii) | Mextral P507 | O h | 2Eg → 2T2g | Δ O | 844 | 11.8 | 11.8 | 7.11 | −0.31 |
| Cu(ii) | D2EHPA | O h | 2Eg → 2T2g | Δ O | 861 | 11.6 | 11.6 | 6.97 | −0.45 |
| Ni(ii) | LIX 84-I | O h | 3A2g → 3T2g | Δ O | 607 | 16.5 | 16.5 | 19.8 | 9.6 |
| Ni(ii) | Mextral 54-100 | O h | 3A2g → 3T2g | Δ O | 1167 | 8.57 | 8.57 | 10.3 | 0.1 |
| Ni(ii) | Versatic acid 10 | O h | 3A2g → 3T2g | Δ O | 1143 | 8.75 | 8.75 | 10.5 | 0.3 |
| Ni(ii) | Cyanex 301 | O h | 3A2g → 3T2g | Δ O | 727 | 13.8 | 13.8 | 16.5 | 6.3 |
| Ni(ii) | Water | O h | 3A2g → 3T2g | Δ O | 1177 | 8.50 | 8.50 | 10.2 | 0 |
| Ni(ii) | Ionquest 290 (dry)e | T d | 3T1 → 3A2 | 2ΔT | 1178g | 8.49 | 4.24 | 3.40 | −6.80 |
| Ni(ii) | Mextral P507 (dry)e | O h | 3A2g → 3T2g | Δ O | ≈1135f | ≈7.4 | ≈7.4 | ≈8.9 | ≈−1.3 |
| Ni(ii) | D2EHPA (dry)e | O h | 3A2g → 3T2g | Δ O | ≈1135f | ≈7.4 | ≈7.4 | ≈8.9 | ≈−1.3 |
| Ni(ii) | Ionquest 290 (wet) | O h | 3A2g → 3T2g | Δ O | 1258 | 7.95 | 7.95 | 9.54 | −0.66 |
| Ni(ii) | D2EHPA (wet) | O h | 3A2g → 3T2g | Δ O | 1228 | 8.14 | 8.14 | 9.77 | −0.42 |
| Co(ii) | Mextral 54-100 | O h | 4T1g → 4T2g | Δ O | 572 | 17.5 | 17.5 | 13.4 | 7.4 |
| Co(ii) | Versatic acid 10 | O h | 4T1g → 4A2g | 2ΔO | 577g | 17.3 | 8.67 | 6.93 | 0.39 |
| Co(ii) | Water | O h | 4T1g → 4A2g | 2ΔO | 611g | 16.4 | 8.18 | 6.55 | 0 |
a
Point group of the crystal field only.
b
Net ligand field stabilization upon extraction from an aqueous sulfate solution.
c
Calculation elaborated in SI (page S10).
d
Residual Cu(ii) signal used.
e
Dried overnight over 3 Å molecular sieves.
f
Peak near edge of measurement range.
g
Peak maximum obtained from spectral deconvolution with uncertainty of approx. 2% on both λmax and derived quantities.