Proton NMR shifts

The pattern K j < K P < K° and X > X° > X is also clearly shown in the correlation of the proton nmr shifts of substituted phenols in DMSO solution. The o and p- substituent effects are best fitted by the a (A) parameters (cf. para set no. 24 of Table VI), whereas the m- substituent effects are best fitted by parameters. The following fitting parameters are... 

In line with its importance in characterization, this section has been expanded and updated and includes a more detailed analysis than that in CHEC-II(1996) and CHEC(1984), which contain, nonetheless, important data on proton NMR shifts of C-3- and C-5-unsubstituted fully conjugated 1,2,4-oxadiazoles. A major advance since CHEC-II(1996) is the appearance of a large amount of fully assigned 13C data for C-3/C-5-disubstituted fully conjugated 1,2,4-oxadiazoles <1996JHC1583,... 

Table II. Proton NMR Shifts (ppm) of Parasorbic Acid Glucoside, 3, and its Aglycone, 4...

Useful applications of the Evans proton NMR shift method have permitted the determination of effective magnetic moments peff (see Section 8) and spin multiplicities for several high-spin radical-cation species.This work makes available a simple procedure for such assignments when the spin carriers are stable in solution. 

Table 4 Inner Proton NMR Shifts of the Unrestricted Hetero[17]annulenes (78AHC(23)55)...

The proton NMR shifts of diad, triad, and tetrad protons in an isolated chain of PP are calculated, taking into account its configurations and conformations using Pople s approximation. The agreement between the observed and calculated results, however, is insufficient with respect to the large difference between syn and anti protons and the order of tetrad protons. Here, a priori probabilities of specified conformations necessary to the estimation of the chemical shifts are calculated using Flory s matrix method. 

Proton NMR shifts have been interpreted in terms of a ring current, and some coupling constants also indicate aromatic properties. Boron-11 shifts alone can apparently not be used as criteria of aromaticity, in the same way that carbon-13 shifts are not meaningful. 

Proton NMR Shifts of certain Restricted Hetero[1 3]annulenes and Related Models"... 

Select Proton NMR Shifts of Certain Unrestricted Hetero[ 1 7]annulenes ... 

Carbon-13 and Proton NMR Shift Assignments and Physical Constants of Diterpenoid Alkaloids... 

---