Spin-donicity

Starting from Equation 10.32, Perez et al. [21] defined spin-donicity and spin-philicity. Following a variational calculation, as used by Parr et al. [22] to define the electrophilic power, they obtain, for the maximum change in energy (AZsmax) when the system modifies its spin number from Ns to Ns + AiVs in a reservoir of spins, ... 

In the direction of decreasing spin multiplicity (A1VS < 0), the spin-donicity can be defined as... 

A large spin-donicity number is expected when the energy difference is smaller between the triplet and singlet states. Thus, spin-philicity and spin-donicity are also a measure of the energy differences between singlet and triplet states, furthermore, it has been demonstrated the applicability of these reactivity indexes in the prediction of the spin transfer observed in the spin-catalysis phenomenon [21], Equivalent quantities at fixed Ns ([Pg.150]

Spin potential, spin hardness, spin-donicity, and spin-philicity indexes have also been applied successfully to other specific problems [19,23,24]. 

There is no more research on the analysis or applications of SP-DFT generalized Fukui functions, per se. Instead, condensed-to-atoms SP-DFT Fukui function schemes have been developed and applied to different chemical reactivity problems. In these schemes, the information of the Fukui functions is condensed on an atomic position. In addition, the Fukui function/ (r) is related with the extension of global to local spin-donicity and spin-philicity, defined as [20]... 

Olah, J., De Proft, F., Veszpremi, T., and Geerlings, P. 2004. Spin-philicity and spin-donicity of substituted carbenes, silylenes, germylenes, and stannylenes. J. Phys. Chem. A 108 490-499. 

Perez, P., Andres, J., Safont, V.S., Tapia, O., and Contreras, R. 2002. Spin-philicity and spin-donicity as auxiliary concepts to quantify spin-catalysis phenomena. J. Phys. Chem. A 106 5353-5357. 

We discussed mainly some of the possible applications of Fukui function and local softness in this chapter, and described some practical protocols one needs to follow when applying these parameters to a particular problem. We have avoided the deeper but related discussion about the theoretical development for DFT-based descriptors in recent years. Fukui function and chemical hardness can rigorously be defined through the fundamental variational principle of DFT [37,38]. In this section, we wish to briefly mention some related reactivity concepts, known as electrophilicity index (W), spin-philicity, and spin-donicity. 

These indices have been used to study the reactivity for a series of chlorobenzenes and a good correlation is observed, for example, between W and toxicity of chlorobenzene [41]. For a detail discussion of this concept and its applications, we refer the readers to a recent review [41,42]. For studying intramolecular reactivity, these philicity indices and local softness contain the same information as obtained from the Fukui functions, because they simply scale the Fukui functions. In some cases the relative electrophilicity and relative nucleophilicity may be used although they provide similar trends as s(r) and co(r) in most cases [43]. In the same vein, the spin-donicity and spin-philicity, which refer to the philicity of open-shell systems [44], could also be utilized to unravel the reactivity of high-spin species, such as the carbenes, nitrenes, and phosphinidenes [45]. 

Finally, worth specifying that the presented line of systematic formulations of the density functional reactivity indices can be in principle continued when also the expansions containing higher order terms in potential are considered through the nonlinear electronic responses (Senet, 1996, 1997). The recent effects as the spin-philicity and spin-donicity in spin-catalysis phenomena can be rationalized on such generalized analysis (Perez et al., 2002). Therefore, this way, also a closely diagrammatical theory of the absolute /, //, IP, and EA can be built up with increasing accuracy in the non-local effects that the softness kernel approximation may induce. 

While solvent effects are small for the ring redox ( 0.2 V), the effect of donor solvents which stabilize the higher oxidation state is marked for the metal redox, especially so for those of low-spin d6/d7 and d1jd%. There is a linear relationship between E° for the Feu/I couple and the Gutmann donicity number. The Com u and Cou/I couples shift positively as the pof substituted pyridine, as solvent, decreases and the ring oxidation precedes the CoIII/n couple in noncoordinating solvents such as CH2C12. 

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