15N-NMR chemical shift

Table 10. 15N-NMR Chemical Shifts (5) of Methyl-Substituted Tetrazoliums 130-132 ...

Table 4 Experimental and ab Zn/ffo-calculated 15N-NMR chemical shifts of the 4H-and 9aH-tautomers of a quinolizine system...

SN NMR has been used to study the mechanism of the photochemical reaction of 5-phenyl-l,2,4-thiadiazole (see Section 5.08.5.2). 5-Phenyl-l,2,4-thiadiazole-4-1SN and 3-phenyl-l,2,4-thiadiazole-2-1SN were synthesized. The 15N NMR chemical shifts reported for the 4-position derivative was +302.2 ppm (acetone- ) and for the 2-position derivative +258.4 ppm (CDCI3) relative to a reference of ammonia <2003JOC4855>. 

The vibrational assignments and force constants have been determined from the IR and Raman spectra of S7NH, S415N4H4 and S415N4D4. The 1H and 15N NMR chemical shifts of all the cyclic sulfur imides have been determined by inverse detection methods.202... 

The calculated 13C and 15N NMR chemical shifts, using the IGLO-HF and GIAO-MP2 methods, however, deviate substantially from the experimental results. This is in contrast with the previously reported results on protonated guanidines 113... 

C and 15N NMR chemical shifts were calculated for protonated diazomethane [CH3N=N]+ and the cyanodiazonium ion [N=CN=N] +. 142 For the C-protonated diazomethane, which is more stable than N-protonated species, the IGLO-HF calculated 13C NMR chemical shift of 54.1 ppm agrees with the experimental value of 44.5 ppm. 15N NMR chemical shifts were calculated as 237.9 and 379.9 ppm. 

Table 3 13C and 15N NMR chemical shifts of unsubstituted [1,2,4]triazolo[1,5-a]pyrimidine A and [1,2,4]triazolo[3,2-a]-pyrimidine B measured in DMSO-d6 solutions... 

The low values obtained from dipole-moment measurements119-124 and ultrasonic measurements171 together with the low value (AG° 1.4 kcal mol-1) derived from a comparison113 of 15N-NMR chemical shifts in systems such as 125 and 126 and in 127 and 128 with the small 15N-NMR... 

Table 16 l4N and 15N NMR Chemical Shifts of Typical Azines and their Derivatives1... 

These results enabled one to employ the solution-phase 15N NMR chemical shifts for estimating of the length of the Sk— N bond in solute silatrane patterns28,263,266,2711. This approach made use of equation 53, which was derived from the corresponding solid-state and gas-phase data263 ... 

TABLE 7. 29Si and 15N NMR chemical shifts of triazasilatranes XSi(NHCH2CH2)3N in CDC13418... 

C 155.3 versus 149). Deshielding was also found in the 15N NMR chemical shifts. Structure 396 is the calculated structure of tetraprotonated guanidine. The four localized positive charges are, obviously, highly unfavorable. 

Simply speaking, that is the continued purpose of the second edition of this book - to provide you, the working organic chemist, with virtually everything you need to know about fluorine NMR, including an understanding of the impact of fluorine substituents upon proton and carbon NMR, and new in the second edition, upon 31P and 15N NMR chemical shifts and coupling constants, to the extent that such data are available. 

The 1H, 13C, and 15N NMR chemical shifts of the (Z)-phenylhydrazones of 5-alkyl-and 5-aryl-3-benzoyl-l,2,4-oxadiazoles have provided information on the ground-state electronic distribution.27 The effects of the substituents on the chemical shifts of N(4) and C(5) correlate with kinetic results of the rearrangement of 1,2,4-oxadiazoles to 1,2,3-triazoles (Boulton-Katritzky reaction) support the importance of the leaving group. 

Fig. 1. Variation of1H- and 15N-NMR chemical shifts with the trans-ligand in Ptn-NH, PtII-NH2...

Table 2. Variation of 15N-NMR Chemical Shifts with the trans-Ligand in Pt-NH3, NH2 and ...

The dependence of NMR chemical shifts on the molar ratio of complex components may be used for studies of the stoichiometry of the complex (252,256,258,263) (Fig. 1). The resonance of some nuclei of the electron donors changes considerably on complexation with silanes. Particularly large changes are observed for the 15N resonance ( 100 ppm upfield) since the paramagnetic component of the 15N-NMR chemical shift is eliminated on quarternization of nitrogen. Mixing of equimolar amounts of pyridine and triphenylsilyl perchlorate was demonstrated to lead to a shift of the 15N-NMR signal from 314.0 to 216.8 ppm, which was taken as evidence for the formation of a 1 1 ionic complex (18). 

Table 23 15N NMR chemical shifts for ring nitrogens of azoles and their oxygen and sulfur derivatives...

Figure 20 15N NMR chemical shifts of representative oxygen and sulfur heterocycles.

Table 3.34 Calculated (B3LYP/6-311G+) 15N NMR chemical shifts of nitrobenzotriazolesa...

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