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Pyramidal methyl group

Figure 6. Hydrogen—hydrogen contacts versus angle of rotation for the pyramidalized methyl group of enone Of the nine... Figure 6. Hydrogen—hydrogen contacts versus angle of rotation for the pyramidalized methyl group of enone Of the nine...
Describe and draw (using cartoons) how the three group orbitals for a pyramidal methyl group (Figure 1.8) can be linearly combined to give orbitals similar to the individual ct bonds formed from sp hybridized carbon atoms and hydrogen Is orbitals. [Pg.63]

Pyramidal nitrogen is favorable for slow inversion. In this case, two methyl groups in the SilV Bu fragment are nonequivalent, whereas two SiMej groups are, on the contrary, equivalent. However, any two identical substituents at the nitrogen atom become nonequivalent in the presence of the asymmetric center G attached to the C,C double bond. [Pg.659]

In the course of the reaction, the nitrite ion leaves the primary anion-radical. This produces the cyclohexyl radical in the pyramidal configuration. The vicinal methyl group sterically hinders the conversion of the pyramidal radical into the planar one. With a high concentration of the nucleophile, the rate of addition exceeds the rate of conversion, that is, Then the entering PhS group... [Pg.324]

Interconversions of acychc carbon-centered radicals between n and a types are low-energy processes. The methyl radical is planar, but increasing alkyl substitution at the radical center results in an increasing preference for pyramidalization. The ferf-butyl radical is pyramidalized with the methyl groups 10° from planarity (the deviation from planarity for a tetrahedral atom is 19°) and a barrier to inversion of 0.5 kcal/mol. When a radical center is in a carbocycle, a planar radical is favored for all cases except the cyclopropyl radical, and the barrier for inversion in cyclopropyl is only 3 kcal/mol. ... [Pg.122]

Figure 25. (a) Steric compression accompanying pyramidalization at Cs. Note the interaction between methyl groups of adjacent molecules as the reaction occurs. Substituents have been omitted. (b) Stereoview of the same phenomenon in a molecule carrying OAc group at y position. [Reproduced with permission from S. Ariel, S. Askari, S. V. Evans, C. Hwang, J. Jay, J. R. Scheffer, J. Trotter, L. Walsh, and Y. F. Wong, Tetrahedron 43, 1253 (1987).]... [Pg.120]

In the square pyramidal complex [Ni(Me4cyclam)N3](C104) (379) (Me4cyclam is 1,4,8,11-tetramethylT,4,8,ll-tetraazacyclotetradecane) the coordinated azide anion is on the same side of the four methyl groups with the nickel atom 33 pm from the N4 plane. The five- and six-membered chelate rings are in the usual gauche and chair conformations respectively.2681 This complex is labile in comparison with the very inert dinuclear complex... [Pg.239]

Complexes ZnL(ClC>4)2 and ZnLCl(C104) (L = tetramethylcyclam) have been isolated.227 The latter contains the five-coordinate ZnLCl+ cation for which NMR results indicate a square pyramidal configuration with the chlorine in the apical position and all four methyl groups on the same side of the plane. [Pg.937]


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Methyl group

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