Table 1.
Selected data for 1‐H2 and metal complexes with the 1 2− ligand.
|
Complex |
1‐H2 |
1‐Mg |
1‐Ca |
1‐Sr |
1‐Ba |
1‐Eu |
|---|---|---|---|---|---|---|
|
d(Fe⋅⋅⋅M) [Å] |
– |
3.4255(6) |
3.1129(6) |
3.3204(5) |
3.4537(4) |
3.3229(5) |
|
Σ(covalent radii) [Å][a] |
– |
2.73 |
3.08 |
3.27 |
3.47 |
3.30 |
|
r(M2+) 6‐coordinate [Å][b] |
– |
0.72 |
1.00 |
1.18 |
1.36 |
1.17 |
|
d(M⋅⋅⋅Fe)−r(M2+) [Å] |
– |
2.706 |
2.113 |
2.140 |
2.094 |
2.153 |
|
Cp/Cp tilt angle [°] |
0.00(3) |
2.99(7) |
7.09(8) |
6.97(8) |
15.23(11) |
7.24(12) |
|
δHα/δHβ Δδ [ppm][c] |
3.82/3.89 0.07 |
3.86/3.96 0.10 |
3.83/3.98 0.15 |
3.73/4.11 0.38 |
3.60/4.15 0.55 |
– |
|
Absorbance UV/Vis [nm][d] ϵ [L mol−1 cm−1] |
450 198 |
455 275 |
506 602 |
479 484 |
474 651 |
447 679 |
|
1st Ox. pot. vs. Fc/Fc+ [V] |
−0.77 |
−1.57 |
−1.67 |
−1.75 |
−1.75 |
– |
|
Fe⋅⋅⋅M DFT [Å] |
– |
3.259 |
3.061 |
3.198 |
3.442 |
– |
|
ρ(r) bcp Fe⋅⋅⋅M [e Å−3] |
– |
– |
0.115 |
0.101 |
0.121 |
– |
|
∇2 ρ(r) bcp Fe⋅⋅⋅M [e Å−5] |
– |
– |
0.964 |
0.819 |
0.602 |
– |
|
H(r) bcp Fe⋅⋅⋅M [Hartree Å−3] |
– |
– |
−0.005 |
−0.002 |
−0.015 |
– |
[a] Covalent radii taken from ref. 27. [b] Ionic radii for 6‐coordinate M2+ ions taken from ref. 16. [c] Chemical‐shift differences measured in C6D6 (1‐H2), C6D6/[D8]THF (1‐Mg) or [D5]pyridine (1‐Ca, 1‐Sr, 1‐Ba). [d] Measured in pyridine solution. The signal for 1‐Eu is superimposed with the very strong absorbance for EuII which also forms intensely red metallocenes.