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One‐ and two‐dimensional multinuclear magnetic resonance study of azaphospholes; sign determination of J ( 15 N, 1 H), J ( 31 P, 1 H), J ( 31 P, 13 C), J ( 31 P, 15 N); Application of hahn‐echo extended pulse sequences
Author(s) -
Wrackmeyer Bernd,
Kupče ĒRiks,
Schmidpeter Alfred
Publication year - 1991
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260291013
Subject(s) - chemistry , heteronuclear molecule , coupling constant , nuclear magnetic resonance spectroscopy , resonance (particle physics) , analytical chemistry (journal) , crystallography , yield (engineering) , nmr spectra database , spectral line , spectroscopy , nuclear magnetic resonance , stereochemistry , atomic physics , physics , quantum mechanics , thermodynamics , particle physics , chromatography , astronomy
Various 1,2,3‐ and 1,3,4‐diazaphospholes (1 to 4), a 1,2,3,4‐triazaphosphole (5) and two 1,2,3‐diazaphospholium chlorides (6, 7) have been studied by 13 C, 15 N and 31 P NMR spectroscopy. The absolute signs [based on 1 J ( 13 C, 1 H) > 0] of numerous coupling constants [e.g., 1 J ( 31 P, 13 C) < 0, 1 J ( 31 P, 15 N) > 0] have been determined by combining information from one‐dimensional selective 1 H{ 31 P}, 13 C{ 31 P} and two‐dimensional (2D) 13 C/ 1 H, 15 N/ 1 H and 31 P/ 1 H heteronuclear shift correlations. H ahn‐ e cho e xtende d (HEED) pulse sequences have been applied to one‐ and two‐dimensional 31 P NMR measurements. In 1D 31 P NMR spectra, 1 J ( 31 P, 15 N) coupling constants can be conveniently determined. The corresponding HEED 2D 31 P/ 1 H experiments yield, in addition, the long range n J ( 15 N 1 H) ( n = 2,3) coupling constants (and their relative signs). Furthermore, isotope shifts, 1 Δ 15/14 N, on 31 P resonances were measured. The low frequency shifts (−0.072 to −0.114 ppm) observed here for two‐coordinate phosphorus compounds 1 to 7 are much larger than those previously reported for P(V)‐ and three‐coordinate P(III) compounds.