Shift R

Suppose a shear stress r causes a linear shift r Q of the energy level of the first state and a shift - r Q of the second state, Q being the activation volume. Then the differential equation for the occupation of state 1 is given by... 

The cycloadduct obtained from ethyl diazoacetate and the cyclic phosphaalkene 9-ferf-butyl-1,3-diphenyl- 10-phospha-1,3-etheno- 17/-benzopyran-4(37/)-one underwent spontaneous [3-1-2] cycloreversion and produced ethyl 5-tert-butyl-1,2,4-diazaphosphole-3-carboxylate (163). Still another transformation was found for P-trimethylsilyl-substituted diazaphospholes system 94, which suffered dediazonia-tion under the cycloaddition conditions and yielded phosphaalkene 95 (162) (Scheme 8.22). It was proposed that N2 extrusion and SiMe3 migration occur in concert. On the other hand, the cycloaddition products derived from phosphaalkene 93 and 2,2-dimethyl-1-diazopropane or diazo(trimethylsilyl)methane simply underwent tautomerization to the corresponding A -phosphapyrazoline (162) (94, R = f-Bu H shift R = SiMe3 SiMe3 shift). 

A discussion of this formula for all values of l is given by Caroli (1967). We shall limit ourselves to the case where J=0 and where the phase shift r , due to a potential V0 finite within a volume Q0, is small. In this case we write... 

The combination of steps 1 and 2 corresponds to a 1,2 hydride shift (R = H) or a Wagner-Meerwein rearrangement (R = alkyl). The intermediate bridged nonclassical structure... 

Quantum theory of scattering. The differential scattering cross section for isotropic potentials is given by the scattering phase shifts r e as... 

Compound C Proton chemical shift r Coupling constant References... 

Table 5.43. 13C Chemical Shifts (r)c in ppm) of Methyl Palmitoleate (Solvent CDC13)...

Table 5.48. Structure, Schematic Representation of the Biosynthetic Incorporation of [l-13C]-Acetate ( ), [2-13C]-Acetate ( ), [Methyl-,3C]methionine (A), and [l-13C]Gly-cine (A) ([2-I3C]-Acetate Incorporation at C-31, C-32, C-33 ( ) See Text) and 13C Chemical Shifts (r)c in ppm Solvent CDC13) of Myxovirescin At [1016],...

Fig. 2.6 Wavefunctions of H and alkali atoms. The lower potential of the alkali introduces the phase shift r, as shown, leading to the depression of the energies of alkali, low i states relative to those of H (from ref. 1).

QDT provides a framework which relates a few energy independent parameters to a wealth of spectroscopic data. It is used both as an efficient way to parametrize data and as a way of comparing theoretical results to experimental data. Which of the several parametrizations to use is usually unimportant for comparing theoretical results to experimental observations, since all the parametrizations are equivalent. On the other hand, if a set of data is to be represented by QDT parameters, it is useful to use the set of parameters which allows the experimental data to be fit with the minimum number of free parameters. For example, to fit ICE data, the phase shifted R matrix approach is by far the most convenient, for the absolute continuum phase does not enter. 

Compound Solvent Hi h2 Chemical shift (r) h3 h4 h5 h6 h7 h8 Refs, to derivatives... 

Compound Chemical shift (r) Coupling constant (Hz) Weak band Strong band... 

TABLE 8. Calculated diamagnetic, paramagnetic and total 29Si chemical shielding tensors a (in ppm, gauge origin at Si) compared with experimental chemical shifts, r... 

Fig. 3.44 Approximate ranges of proton chemical shifts (R = H or alkyl Y = SR, — NR2 X = OR, — NHCO-R, — 0 C0 R, halogen). Data reproduced from L. M. Jackman and S. Stemhell (1969). Applications of Nuclear Magnetic Resonance in Organic Chemistry. 2nd edn. London Pergamon Press, p. 161.

By slow spinning band distillation in each case (R=CH3, CgHg) the two compounds corresponding to the two 31p nmr signals were separated with the major product in both instances having the downfield Up nmr chemical shift (R=CH3 6 31p + 75.1, 36% yield R=C H, 6 31P + 65.9, 58% yield). These compounds were identified spectroscopically ( H and 13c nmr, MS, IR) and by microanalysis as the expected 1,2-oxaphosphol-4-ene derivatives of the reaction of eq (1). ... 

The minor product, having in each instance the more upfield 31p nmr chemical shift (R=CH3, 6 33P + 59.4, 10% yield) R=CgH5 ... 

---