Table 1.
Comparison of Mechanisms I and II (Figure 2) for n-Doping with Dimeric Dopants
| Mechanism | Products | Rate-determining step[a] | Rate law[a] | ΔG‡ limited by [a] | Δ S ‡ [a] |
|---|---|---|---|---|---|
| I | D+ A •– ( + A 2–)[b] | D2 dissociation | d[D2]/dt = −k[D2] | ΔGdiss(D2) | >0 |
| II | D+A•– | electron transfer | d[D2]/dt = −k[D2][A] | F{E(D2+/0)–E(A0/−)} | <0 |
[a]
Assuming that in each case the first step is rate-determining.
[b]
If E(A•–/A2–) is at less reducing potential than Eeff(D2/0.5D•) then A2– can be formed if sufficient D2 is present. Since E(A•–/A2–) is generally significantly more reducing than E(A/A•–), formation of A2– via mechanism II will be much slower than the initial formation of A•–, but at a similar rate if mechanism I is operative.