The first two paragraphs, Fig. 2 and Table 3 on page 6784 should be replaced by the following:

The electrochemical behaviour of a 1 mM DCM solution of the imidazolobenzotriazinyls 4a–i and the oxazolobenzotriazinyl 5 was probed by cyclic voltammetry using n-Bu₄NBF₄ as supporting electrolyte. The redox behavior of the imidazolo-fused radicals 4a–i was previously shown to differ from the typical redox behavior of non-fused 1,2,4-benzotriazinyls in that their reductions were quasi-reversible. However, we have now attributed this quasi-reversible behavior to wet electrolyte. With dry electrolyte both the oxidation (0/+1) and reduction (–1/0) processes of the radicals 4a–i were fully reversible (Table 3 and Fig. 2, see ESI for revised Fig. S1–S10).



Fig. 2 Cyclic voltammograms of (a) imidazolobenzotriazinyl 4a (1 mM) and (b) oxazolobenzotriazinyl 5 (1 mM), n-Bu₄NBF₄ 0.1 M, DCM, ca. 20 °C, 50 mV s^–1.


Table 3. Cyclic voltammetry data of Blatter, thiazolo-, imidazolo- and oxazolobenzotriazinyls 1, 3, 4a–i and 5, respectively<sup>a


a</sup> The concentration of radicals used was 1 mM in DCM. A 0.1 M DCM solution of n-Bu₄NBF₄ was used as electrolyte. Reference electrode = Ag/AgCl; scan rate = 50 mV s^–1. Ferrocene was used as internal reference (0.352 V). ^b Reduction irreversible. ^c E_cell = E_1/2^0/+1 – E_1/2^–1/0.

The imidazolobenzotriazinyls 4a–i have half-way oxidation potentials (E_1/2^0/+1 = 0.02–0.10 V) that are lower than those of the thiazolobenzotriazinyls (E_1/2^0/+1 = 0.18–0.38 V), indicating a more facile donation of an unpaired electron. Conversely the thiazolobenzotriazinyls are better acceptors since their half-way reductions potentials (E_1/2^–1/0 = –0.76–0.93 V) are lower than those of the imidazolobenzotriazinyls 4a–i (E_1/2^–1/0 = –0.93–1.03 V). As anticipated, substituents on the 4-position of the imidazole N-phenyl ring, do not significantly alter the electron distribution around the benzotriazinyl core and have therefore minimal effect on the oxidation and reduction potentials evident by the narrow range of their E_1/2^0/+1 and E_1/2^–1/0 values. For radical 4h the second reversible reduction (E_1/2^–2/–1 = –1.16 V) is attributed to the reduction of the NO₂ group. The fully reversible and low oxidation potentials (E_1/2^0/+1 = 0.02–0.10 V) of the imidazolobenzotriazinyls 4a–i coupled with their low E_cell values (0.99–1.13 V) and their planar spin-bearing acene core make them good donor candidates for charge-transfer salts, e.g., the pressure-dependent semiconductor complex Blatter radical 1:TCNQ,³ and as cathodic components in organic radical batteries,⁴ or as redox mediators in dye sensitized solar cells.⁵

The authors wish to acknowledge Miss Georgia A. Zissimou, who discovered the error and assisted in the production of the corrected data.

The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

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