Newman diagrams

Newman-diagram depict rotation about a C-C bond eclipsed (high eneigy), anti (low energy), gauche (intermediate energy)... 

TWIST is defined203 as the angle between the bisectors of the 1,1- and 2,2-substituent angles on a Newman diagram of the olefin. b Singlet. c In DMSO-d6. 

Newman diagram, molecule viewed along C(6)—C(5) bond (also applies to formulae 38 and 39). 

The rotamers are not at all evenly distributed among the possible staggered dihedrals. The reason for this can be seen in the Newman diagram in... 

Newman diagrams for protein backbone-side-chain interactions. (A) Backbone-independent interactions, looking down the Ca-C/f bond from Cfl certain combinations of X and Xi are forbidden because of close interactions between C<5 and backbone N and C of the same residue. In the lower diagram, the X2 = 180° rotamer is pointing towards the viewer. The four i, 2 combinations which... 

Figures.28. Conformation of hydrochloride of tetracycline derivatives Newman diagram depicts view...

Consider next a normal butane molecule. Its end methyl groups can assume three spatial conformations (1) they can both be at 12 o clock positions relative to the central (interior) C—C bond cis rotamer) (2) one can be at 12, the other at 6 o clock trans rotamer) or one can be at 12 and the other at 2 or 10 o clock (mirror-image gauche rotamers). This can be visualized by means of Newman diagrams, which are projections of the ligands onto a plane perpendicular to the central C-C axis, the nearer of the central C atoms being indicated by a point, the farther, by a circle (Figure 3). 

Now, consider 2-methylbutane, whose Newman diagrams are shown in Figure 4. It is impossible for the end methyl groups to configure themselves so that all are trans to one another. In the two gauche conformations, two methyls are gauche to one another. 

Newman projections are helpful in determining the proper dihedral angles for the fluorines and hydrogens. Here are diagrams for the RR isomer, looking down the C-C bond in both directions ... 

A similar process, using the Newman projection diagram on the right, which places C2 in front of Cj, and uses Clj as the third atom for the dihedral angles, results in the last two lines of the Z-matrix ... 

For example, chemists are required to interpret diagrams of a molecule of cyclohexane, or of substituted cyclohexanes, when it is represented as a flat-looking hexagonal projection, or as a side-on view to show the chair form, or as a Newman projection (Fig. 1.8). 

FIGURE 22. Top Labels of the four localized basis w-orbitals of [4.4]spirononatetraene 247 and Newman projection defining their relative phases. Middle Newman projections of the four linear combinations ld2(tr), b <7T) and 1 c(jt). defined in equation 59. Bottom Correlation diagram showing the splitting due to spiroconjugation between the butadiene moieties in 247... 

Figure 5.102 Tensile stress-strain diagrams for two SMC compounds 25 wt% fiber, bottom, and 65 wt% fiber, top. Reprinted, by permission, from Composite Materials Technology, P. K. Mallick and S. Newman, eds., p. 45. Copyright 1990 by Carl Hanser Verlag.

TABLE 9. Conformational structures (a) and Newman projection diagrams (b) of (IS,25)- and (IR,2ft)-cyclohexane diol. Bis-p-dimethylaminobenzoate derivatives (c), bisignate CD Cotton effect data and torsion angles (d)14... 

Figure 4.18 Cornell Electron Storage Ring. Photo and diagram reprinted with permission of Floyd R. Newman Laboratory of Nuclear Studies, Cornell University. For a virtual tour of CHESS, see the CMCC Home Page on the World Wide Web.

B-ll. Which point on the potential energy diagram is represented by the Newman projection shown ... 

Fig.C. (a) a proton (b) orbital diagram illustrating orbital interactions (c) Newman projection.

Table XI. Conformational structures (a and b) and Newman projection diagrams (c and d) of (15,25) and (lR,2R)-cyclohexane diol (a) and their bis-p-dimethylaminobenzoate derivatives (b). CD data for the bisignate Cotton effects of the latter are shown below.

In addition to angle strain, cyclopropane has a significant amount of torsional strain. This can best be seen by looking at a Newman projection down any of the C—C bonds. As can be seen in this diagram, each C—C bond is held in an eclipsed conformation by the rigidity of the molecule. 

The ene is delivered to the bottom face of the enone, as its tether (Chapter 33) is too short for it to reach the top face, and a cis ring junction is formed. The stereochemistry of the third centre is most easily seen by a Newman projection of the reaction. In the diagram in the margin we are looking straight down the new C-C bond and the colour coding should help you to see how the stereochemistry follows. 

Let us first neglect 02 and 03, and consider only rotation about C(2)-C(3). A number of remarkable conformers and their torsion angle are displayed in diagrams LXVII using Newman projection. The diagrams show three eclipsed conformations... 

In addition to Fischer and perspective diagrams, physical organic chemists use Newman and sawhorse diagrams to show conformations as well as configurations of two-centre compounds. 

FIGURE 12.7. Fischer and Newman projections of enantiomers (mirror images of each other). One enantiomer is on the left and the other is on the right, divided by a vertical line (a mirror perpendicular to the plane of the page), (a) Fischer diagram, and (b) Newman projection. 

In 6 years there has been a number of papers written on the interpretation of the concentration (dose)-response curve. Results from the studies of D. Moore, R Caux, and M. Newman have demonstrated that curve-fitting is superior to the calculation of no-effect or low-effect values. G. Stephenson and colleagues have also published a flow diagram describing in detail the steps necessary to fit a curve to toxicity data. 

Phase diagrams of polymer blends and solutions (open symbols are binodals and filled symbols are spinodals). (a) Polymer blends of poly(vlnyl methyl ether) (A/ = 51 500 g mol ) and various molar masses of polystyrene (circles have Af = 10 000 g mol, squares have M = 20400 g moP, hexagons have M=5l 000 g mol , diamonds have A/ = 200000 g moP ), data from T. K. Kwei and T. T. Wang, in Polymer Blends, Vol. 1 (D. R. Paul and S. Newman, editors). Academic Press, 1978. (b) Polyisoprene solutions in dioxane------... 

Figure 2.6 (a) Schematic diagram showing two adjacent carbons, C and C +i, in the main chain of isobutylene, (b) Newman projections of staggered conformations of adjacent carbons in the main chain. 

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