Medium effects on nitrogen nuclear shielding in methyl nitrate and methyl isothiocyanate assessed by the solvaton model

Solvent induced variations in nitrogen NMR shieldings of some oxime systems as a test of the Solvaton model of non-specific molecular interactions

“…[27][28][29] Very pure and dry solvents were used in the NMR measurements as reported previously. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] The solutions were prepared and handled under a dry argon atmosphere in glove bags. The 14 N shielding measurements were taken on a Bruker AM500 Spectrometer at 35 + 0.2 ЊC, as maintained by a variable temperature unit, at a frequency of 36.14 MHz.…”

Solvent Effects on Nitrogen Chemical Shifts

“…9) show a low, <3.6 ppm, solvent dependence [43]. Hydrogen bond donor solvents, such as trifluoroethanol cause a slight increase of δ 15N of Figure 9 The structures of N,N-dimethylmethane-sulphonamide (33), N,Ndimethylbenzene-sulphonamide (34), benzene-sulfonamide (35), N,Ndimethylmethanesulphinamide (36), tetramethylurea (37), methylurea (38), tetramethylthiourea (39), thiourea (40), N,N-dimethylacetamidine (41), N-methylacetimidate (42), and methylacetimidate (43). 34 (Table 3), implying a decrease in the double-bond character of its sulfurnitrogen bond as a result of hydrogen bond donation to the oxygen of the sulphonyl group, rather than to its nitrogen.…”

“…5), as a function of solvent, is $5 ppm, and is thus approximately half of that of nitromethane (1) [33]. The terms a and d of 11 are insignificant (Table 2), whereas its somewhat larger negative term s implies the influence of solvent polarity on its electron distribution.…”

“…The nitrogen chemical shift of 1-methyl-2-pyrrolidinone (31) and 1-ethyl-2-pyrrolidinone (32) slightly decrease in hydrogen bond donating solvents (Table 3) [42], which agrees to term a being significant for these compounds ( Table 2). The δ 15N of N,N-dimethylmethane-sulphonamide (33), N,Ndimethylbenzene-sulphonamide (34), and benzene-sulfonamide (35, Fig. 9) show a low, <3.6 ppm, solvent dependence [43].…”

Solvent‐induced variations in nitrogen NMR shieldings of tert‐butyl isocyanide as a probe for solvent polarizability–polarity

“…- 6 These consist of both non-specific interactions relating to solvent p~larizability-polarity'-~ and specific interactions where solvent molecules may act as either hydrogen bond donors or acceptors. An important aspect of these observations is that nitrogen NMR can be employed in order to assess the validity of various empirical and semi-empirical scales of bulk solvent properties.…”