Chem3D 8.0 Manual - CambridgeSoft

Administratormeta>para>ortho, where ortho substitution showsthe greatest reduction of negative charge on thephenoxy oxygen. You can reason from this data thatthe phenoxy ion is stabilized by nitro substitution atthe ortho position.Phenoxidep-Nitro m- Nitro o-NitroC1 0.39572 C1 0.41546 C1 0.38077 C1 0.45789C2 -0.46113 C2 -0.44929 C2 -0.36594 C2 -0.75764C3 -0.09388 C3 -0.00519 C3 -0.33658 C3 0.00316C4 -0.44560 C4 -0.71261 C4 -0.35950 C4 -0.41505C5 -0.09385 C5 -0.00521 C5 -0.10939 C5 -0.09544C6 -0.46109 C6 -0.44926 C6 -0.41451 C6 -0.38967O7 -0.57746 O7 -0.49291 O7 -0.54186 O7 -0.48265H8 0.16946 H8 0.18718 H8 0.21051 N8 1.38805In general, these atomic point charges give a betterindication of likely sites of attack when compared toatomic charges derived from the Coulson densitymatrix (Charges) or Mulliken population analysis(Mulliken Charges). The uses for electrostaticpotential derived charges are generally the same asfor atomic charges. For examples, see “Charges” onpage 163.There are two properties available for calculatingatomic point charges: Wang-Ford Charges andElectrostatic Potential.Wang-Ford ChargesThis computation of point charges can be used withthe AM1 potential function only.For information about the elements covered usingthe AM1 potential function see ‘Chapter 9:Computation Concepts” and the MOPAC onlinemanual, page 223.H9 0.12069 H9 0.17553 N9 1.31296 H9 0.16911H10 0.15700 N10 1.38043 H10 0.19979 H10 0.17281H11 0.12067 H11 0.17561 H11 0.14096 H11 0.13932H12 0.16946 H12 0.18715 H12 0.17948 H12 0.18090O13 -0.70347 O13 -0.65265 O13 -0.71656O14 -0.70345 O14 -0.64406 O14 -0.65424NOTE: For elements not covered by the AM1potential function, use the Electrostatic Potentialproperty to get similar information on elementsoutside this properties range.Below are the keywords automatically sent toMOPAC.Charges From an ElectrostaticPotentialThe charges derived from an electrostatic potentialcomputation give useful information about chemicalreactivity.The electrostatic potential is computed by creatingan electrostatic potential grid. Chem3D reports thepoint charges derived from such a grid.KeywordPMEPQPMEPDescriptionAutomatically sent to MOPAC tospecify the generation of PointCharges from PMEP.Automatically sent to MOPAC tospecify the Wang/Fordelectrostatic Potential routine.166 • Chapter 11: MOPAC Computations CambridgeSoftCompute Properties