Donor-acceptor, intermolecular hardness

Also, the donor-acceptor intermolecular hardness is one-half of the difference between the ionization potential of the donor and the electron affinity of the acceptor. 

Figure 2.11. (A) Relative energies of frontier orbitals of dioxygen and substituted Co ph-thalocyanines. For simplicity, only one electron is shown on the SOMO of the CoPcs. (B) Plot of log k (at constant potential) vs. the donor-acceptor intermolecular hardness for the different O2-C0PC pairs. From ref. [33], reproduced with permission of Elsevier.

Cardenas-Jiron, G.I. and J.H. Zagal (2001). Donor-acceptor intermolecular hardness on charge transfer reactions of substituted cobalt phthalocyanines. J. Electroanal. Chem. 497, 55-60. 

Indeed, all these three indexes are related to the properties of an isolated reactant, that is they do not take into account the selectivity for other species. To this end, a new intermolecular index can be introduced, the donor-acceptor intermolecular hardness ( da) defined as ... 

Table 12.4. Computed Donor-Acceptor Intermolecular Hardness (i/ad. for selected Co(II)-N4 Complexes...

Table 12.6. Gas-Phase Electrophilities (co, eV) and Donor-Acceptor Intermolecular Hardness ( da> eV) of the C0PC-N4 System and its Variations (A) with Respect to the...

Cardenas-Jrron GI, Gulppi MA, Caro CA et al (2001) Reactivity of electrodes modified with substituted metallophthalocyanines. Correlations with redox potentials, Hammett parameters and donor-acceptor intermolecular hardness. Electrochim Acta 46(20-21) 3227-3235... 

Masa J, Schuhmann W (2013) Systematic selection of metalloporphyrin-based catalysts for oxygen reduction by modulation of the donor-acceptor intermolecular hardness. Chem Eur J 19 9644-9654... 

Linares-Flores C, Espinoza-Vergara J, Zagal JH, Arratia-Perez R (2014) Reactivity trend of Fe phthalocyanines confined on graphite electrode in terms of donor-acceptor intermolecular hardness linear versus volcano correlations. Chem Phys Lett 614 176-180... 

In order to define the relative reactivity of the M(II)Pc and M(II)P towards the 2-mercaptoethanol we considered two different reactivity indexes the electro-philicity (co) and the intermolecular hardness ( ad)- The first one is an intramolecular parameter, depending only on the electronic characteristic of the acceptor species, while the second one, defined in terms of both acceptor and donor properties, is an intermolecular parameter. As a consequence, the combined use of these two indexes should give a complete picture of the overall oxidation process. In Figure 12.2, the relative electrophilicity (A ) and intermolecular hardness (A tjDA) with respect to those of the analogous C0-N4 systems are reported. 

The intermolecular donor-acceptor hardness (>/da, as defined by Equation (12.6)), provides a more rigorous description of these nucleophile/electrophile interactions. The /da values for the whole series of N4 macrocycles are collected in Table 12.4 and plotted in Figure 12.6. 

Figure 12.6. Plots of the intermolecular donor-acceptor hardness ( /da> in the gas phase and in aqueons solution for selected Co(II)-N4 complexes (N4 = P, TAP, TBP, Pc and TPP).

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