Heteronuclear Magnetic Double Resonance

NMR nomenclature. Nuclear spin properties and conventions for chemical shifts(IUPAC Recommendations 2001)

“…Measurements of such relations have been reported sporadically since the time of early double-resonance experiments [49], and it has been proposed to relate the separate reference frequencies to a primary standard originally defined for a magnetic field such that the 1 H TMS signal is at exactly 100 MHz. These frequencies have been given [49] the symbol Ξ (capital Greek xi), and some tabulations have been presented [5,14,[50][51][52]. However, it is clearer and more appropriate for users of modern high-field NMR spectrometers simply to define Ξ as the ratio of the secondary (isotope-specific) frequency to that of 1 H in TMS in the same magnetic field.…”

NMR Nomenclature: Nuclear Spin Properties and Conventions for Chemical Shifts

“…Measurements of such relations have been reported sporadically since the time of early double-resonance experiments [49], and it has been proposed to relate the separate reference frequencies to a primary standard originally defined for a magnetic field such that the 1 H TMS signal is at exactly 100 MHz. These frequencies have been given [49] the symbol X (capital Greek xi), and some tabulations have been presented [5,14,[50][51][52]. However, it is clearer and more appropriate for users of modern high-field NMR spectrometers simply to define X as the ratio of the secondary (isotope-specific) frequency to that of 1 H in TMS in the same magnetic field.…”

Synthesis, NMR spectroscopic characterization and structure of a divinyldisilazane‐(triphenylphosphine)platinum(0) complex: observation of isotope‐induced chemical shifts 1Δ12/13C(195Pt)

“…1 J ( 195 Pt, 31 P) > 0 [13] or 2 J( 29 Si, 1 H SiMe ) > 0 [14] ), other absolute signs become available (see Scheme 2 for two examples). Usually, this comparison can be achieved by selective heteronuclear A{M} or M{A} double resonance experiments, [15] or by observing the tilt of relevant cross peaks in two-dimensional (2D) heteronuclear shift correlations. [16] The latter approach is particularly convenient using modern NMR spectrometers with one of the active nuclei being 1 H (= M) and performing 2D A/ 1 H shift correlations, either direct (e.g.…”

“…Bruker DRX 500 was used for 1D and 2D experiments: 1 H, 13 C, 15 N, 31 For EI-MS spectra, Finnigan MAT 8500 spectrometer (ionisation energy 70eV) with direct inlet was used; the m/z data refer to the isotopes 1 H, 12 C, 14 N, 28 Si, 31 P and 195 Pt. Melting points (uncorrected) were determined using a Büchi 510 melting point apparatus.…”

“…1 H,13 C,31 P,29 Si, 195 Pt and15 N NMR data a of the tetramethyldi-Z 2 -vinyldisilazane(triphenylphosphine)platinum(0) 3 J( 195 Pt, 1 H) = 0.6 1 J( 29 Si, 13 C Me(a) ) = 57.2 1 J( 195 Pt, 31 P) = 3609 3 J( 31 P, 29 Si) = 4.9 1 J( 195 Pt, 31 P) = 3609 1 J( 15 N, 1 H) = 70.0 2 J( 29 Si, 1 H) = 6.6 3 J( 195 Pt, 13 C Me(a) ) = 6.5 1 J( 31 P, 13 C ipso ) = 44.4 2 J( 195 Pt, 29 Si) = 45.1 1 J( 195 Pt, 13 C SiC= ) = 155.0 1 J( 13 C Me , 1 H) = 117.5 2.07 (d, CH 3(b) ) 1 Δ 12/13 C( 31 P) = À13 1 J( 29 Si, 13 C Vin ) = 74.3 1 J( 195 Pt, 13 C =CH ) = 113.5.0…”