Geminal C,H spin coupling in substituted alkenes

Microsolvation and sp2-stereoinversion of monomeric α-(2,6-di-tert-butylphenyl)vinyllithium as measured by NMR

“…2-/6-C), 119.536 ( 2 Δ = –0.133 ppm, C-β), 124.70 (C-3/-5), 127.05 (C-4), 140.0 ( 2 Δ = −0.090 ppm, C-1), 141.47 (t, 1 J CD = 23.7 Hz, 1 Δ = −0.318 ppm, C-α), 149.30 (C-2/-6) ppm; 13 C NMR (CDCl 3 , 100.6 MHz) δ 32.30 [qm, 5 Δ = −0.0067(3) ppm, 2-/6-C Me 3 ], 36.79 [ 4 Δ = −0.0056(3) ppm, quart. 2-/6-C], 119.22 [sharp t, 1 J = 157 Hz, 2 J CD = 0 Hz [31], 2 Δ = −0.134(4) ppm, C-β], 124.20 [dm, 4 Δ = −0.0103(2) ppm, C-3/-5], 126.236 [d, 5 Δ = +0.0065(7) ppm, C-4], 139.65 [m, 2 Δ = −0.0845(8) ppm, C-1], 140.05 [t, 1 J CD = 24.0 Hz, 1 Δ = −0.321(2) ppm, C-α], 148.995 [m, 3 Δ = +0.0315(6) ppm, C-2/-6] ppm.…”

Cyclocondensation of n-(prop-2-yn-1-yl)- and n-(penta-2,4-diyn-1-yl)- o-phenylenediamines with phenyl isothiocyanate and carbon disulfide

“…The latter surpasses the vici- Previously in [27], it was shown that the size of the cis-vicinal constant ( 3 J CH ) in similar systems depends little on the structure and lies within 5.0-7.0 Hz limits for both cyclic and acyclic compounds such as methacrylic acid III. But, unlike the vicinal, the geminal coupling constants may vary within wide limits [28]. In particular it was discovered that the geminal constant ( 2 J CH ) increased appreciably on changing the hybridization of the considered carbon atom from sp or sp 2 to sp 3 , which is evidently seen in the example of cyclohexenone IV [28], and also on comparing 2 J CH in 1,3-thiazin-4-ones II and in compound 5a.…”

“…But, unlike the vicinal, the geminal coupling constants may vary within wide limits [28]. In particular it was discovered that the geminal constant ( 2 J CH ) increased appreciably on changing the hybridization of the considered carbon atom from sp or sp 2 to sp 3 , which is evidently seen in the example of cyclohexenone IV [28], and also on comparing 2 J CH in 1,3-thiazin-4-ones II and in compound 5a.…”

Distance‐independent Cross‐correlated Relaxation and Isotropic Chemical Shift Modulation in Protein Dynamics Studies

“…Generally, interpretation of these CCR rates in terms of dynamics models is non‐trivial because dynamics‐induced alterations of the rates are typically much smaller than the rates per se . The quantification of the experimental errors are therefore crucial because they may mask the dynamics effects, and considerable effort has been made to estimate these errors ,. In principle, however, the DD interaction carries the most directly accessible atomistic information as it is directly related to the bond vector connecting the two atoms that interact.…”