1SN measurement

The 1SN- C coupling constants were measured for 1SN 4-labelled 3-methyl- and 3,5,6-trimethyl-1,2,4-triazine <760MR(8)273). They are in the same range as found for other azines. 

TABLE 16. 1SN chemical shifts of nitroso compounds in CDCI3 measured with respect to 4.5M NH4NO3 

Atom% excess, written as APE, measures the abundance above a specified background level. For 1SN, the value of 0.3663 atom % for N in air is commonly taken as the natural background. 

Comparison of the 1SN NMR shifts reveal that the N-3 and N-8 shifts appear at significantly lower fields in contrast to the shifts of N-l and N-4 atoms. The results of these measurements are in good accordance with the earlier study of Grodzicki et al. <1996MRC725>. 

Structure elucidation of three related derivatives of ring system 2 ( temozolomide 9a, mitozolomide 9b, and the related acid derivative 9c) has been carried out by 13C and 15N NMR spectroscopy <1995J(P1)249> (Scheme 2). The 1SN NMR chemical shifts measured in dimethyl sulfoxide (DMSO) solutions are listed in Table 1. For compound 9a, Lowdin charges of the nitrogen atoms have also been calculated and found to have a linear relationship with the experimentally determined chemical shifts of these atoms. The NMR data of 9a have been correlated with those of a series of heterocycles of related structure by the same team <2002MRC300>. 

One technique that has been able to measure hydrogen concentration in a thin film and do a depth profile, without reliance on standards, uses a resonant nuclear reaction technique.16 In this procedure, the nuclear reaction between a hydrogen atom ( H) and an energetic nitrogen-15 atom (1SN) is used. That is 

When Ph15NH2 and Na15N02 are used for preparation and nitrosation of the arylhydrazinium dithiocarbamates 38, each of the nitrogen positions of product 39 may be labeled with 1SN to allow measurement of 1SN-1SN coupling constants (Section 6.08.3.2) <1996JST167>. 

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