Electronegativity chemical potential hardness

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Electronegativity (chemical potential) Hardness / Softness Maximum Hardness Principle (MHP) HSAB (hard and Soft Acid and Base) Principle / 1 , 2 2 1 2 2 S N E HOMO LUMO 2 LUMO HOMO N E
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its.unc.edu 64 DFT Reactivity Indices DFT Reactivity Indices Fukui function N f r r Nucleophilic attack r r r N N f 1 Electrophilic attack r r r 1 N N f Free radical activity 2 r r r f f f
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its.unc.edu 65 Electrophilicity Index Electrophilicity Index Physical meaning: suppose an electrophile is immersed in an electron sea The maximal electron flow and accompanying energy decrease are 2 2 1 N N E 2 2 max N 2 2 2 2 min E Parr, Szentpaly, Liu, J. Am. Chem. Soc. 121 , 1922(1999).
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its.unc.edu 66 Experiment vs. Theory Theory Pérez, P. J. Org. Chem. 2003 , 68 , 5886. Pérez, P.; Aizman, A.; Contreras, R. J. Phys. Chem. A 2002 , 106 , 3964. 2 2 l o g ( k ) = s ( E + N )
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its.unc.edu 67 Minimum Electrophilicity Principle Minimum Electrophilicity Principle Analogous to the maximum hardness principle (MHP) Separately proposed by Noorizadeh and Chattaraj Concluded that “the natural direction of a chemical reaction is toward a state of minimum electrophilicity.” Noorizadeh, S . Chin. J. Chem . 2007 , 25 , 1439. Noorizadeh, S . J. Phys. Org. Chem. 2007 , 20 , 514. Chattaraj, P.K. Ind. J. Phys. Proc. Ind. Natl. Sci. Acad. Part A 2007 , 81 , 871. non- LA 1 2 3 4 5 6 7 A a -0.091 - 0.085 -0.093 -0.093 - 0.088 -0.087 -0.083 -0.090 B b -0.089 - 0.084 -0.088 -0.089 - 0.087 -0.087 -0.0842 - 0.0892 A a -0.172 - 0.247 -0.230 -0.220 - 0.218 -0.226 -0.2518 - 0.2161 B b -0.171 - 0.246 -0.247 -0.233 - 0.221 -0.226 -0.2506 - 0.2157 Yue Xia, Dulin Yin, Chunying Rong, Qiong Xu, Donghong Yin , and Shubin Liu, J. Phys. Chem. A, 2008 , 112, 9970.
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its.unc.edu 68 Nucleophilicity Nucleophilicity Much harder to quantify, because it related to local hardness, which is ambiguous in definition. A nucleophile can be a good donor for one electrophile but bad for another, leading to the difficulty to define a universal scale of nucleophilicity for an nucleophile. A B A B A 2 2 1 Jaramillo, P.; Perez, P.; Contreras, R.; Tiznado, W.; Fuentealba, P. J. Phys. Chem. A 2006 , 110 , 8181.  = -N  - ½ S(  ) 2 Minimizing  in Eq. (14) with respect to  , one has  =-N and  = - ½ N 2 . Making use of the following relation B A B A N
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its.unc.edu 69 Philicity and Fugality Philicity and Fugality Philicity: defined as ·f( r ) Chattaraj, Maiti, & Sarkar, J. Phys. Chem. A 107 , 4973(2003) Still a very controversial concept, see JPCA 108 , 4934(2004); Chattaraj, et al. JPCA, in press . Spin-Philicity: defined same as but in spin resolution Perez, Andres, Safont, Tapia, & Contreras. J. Phys. Chem. A 106 , 5353(2002) Nuclofugality & Electrofugality 2 ) ( 2 A E n 2 ) ( 2 I E e Ayers, P.W.; Anderson, J.S.M.; Rodriguez, J.I.; Jawed, Z. Phys. Chem. Chem. Phys. 2005 , 7 , 1918. Ayers, P.W.; Anderson, J S.M.; Bartolotti, L.J. Int. J. Quantum Chem. 2005 , 101 , 520.
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its.unc.edu 70 Dual Descriptors Dual Descriptors             N N N N f N E E N f r r r r r     2 2 2 2 2 3 rd -order cross-term derivatives     0 2 r r d f         r r r f f f 2         r r r HOMO LUMO f 2 Recovering Woodward-Hoffman rules!
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